From Festool you choices are obviously the ROTEX RO 125 and the ETS 125.

If you're targeting a finishing sander, the ETS 125 would be perfect with its fine 2mm orbit. It's light too, so you can go for hours ...

The ROTEX gives you more options with an aggressive mode, that's also good for polishing. More of a barrel unit in your hands to use.

I was personally considering the Mirka Ceros 125 - but the hassle of the DC transformer and the fiddliness of the vacuum connection are enough to put me off it.

Then you've got every other 5 inch sander on the planet.

(that's my view of the 5 inch sander market - admittedly a little biased from the good experiences I've had)

Kev

I'd definitely consider the Mirka. The downside is that it's expensive, and the hose connection is a bit of a bother but for someone who is looking for a one handed light-weight unit the separate transformer is great because it makes the sander itself light and yet pretty powerful.

The ETS 125 isn't a bad choice - while it is not powerful, you can add something like the Bosch 1250DEVS to your stable if you need it.

Since you'll have to get new sandpaper for a Festool sander anyway, I'd encourage looking at the ETS 150/3. While it's still a fine finish sander, it can be aggressive enough with the right sandpaper on it. It also handles like a dream, and the larger pad size makes sanding go that much faster. I couldn't imagine being without mine.

- Mike

The ETS 125 and RO 125 are probably the worst Festool sanders of their respective category, and combining both only duplicates their lackings.
If you want a finish sander then the DTS400 is a better choice IMO, way more versatile and a tad more aggressive. What is a finish sander good for when it can't reach corners?
The RO 125 (which i returned) was tiring to use, hard to control and yet felt underpowered, THe RO 150 is better, if only slightly, in every way.
The ETS 125 (which i kept, but haven't used since i got a DTS400) is a strange little sander, nice and light, yet it has no guts, the surface needs to be sanded really well with an intermediate sander before considering using the 125. Needless to say i never find it worthwhile to take it out of it's box just to give a microscopic difference in surface quality, and i sand with a ETS 150/5 all the way.

The ETS 150 is the king of Festool random orbital sanders, best combination of power, weight and ergonomics. Personally i prefer the /5 model because it can do anything. It's the basics to start with.

For my next Festool purchase, I've been looking at getting a sander to handle the corners, since I now have ones for everything else. In Paul Marcel's review of the RO 90, he points out that one of the nice things about its delta pad is that you can rotate the abrasive pads as you wear out the tip, making each piece last three times longer. That has me leaning towards the RO 90 as my next purchase—over, say, the DTS 400—pretty much for that reason.

Here's Paul's review of the RO 90:

Festool RO-90 DX Multi-Mode Sander Review

BTW, I'm pretty sure the MultiMaster has dust collection. At least some of the pads and abrasives have holes and there is a dust collection system. Hmm, maybe I should do some testing of this before I spend any more money.

Those two points bothered me too, but with a little creativity I worked out both those issues.  The sander isn't as vibration-free as the Festools but I like the size, and agility of the CEROS.

OP,  if I may ask, where did you buy your cache of Diablo sandpaper?
I recently saw HD was carrying this,  and since they still have their wonderful "return policy" I am hoping you purchased at one of their big orange boxes, as they are pretty good about accepting returns.

and as this has also been pointed out,  you can "buy it and try it" with any FESTOOL...  no strings,  no guilt trip.  buy the Festool tool of your choice, and try it for 30 days.  if for any reason, you wish to send it back,  you'll have no problem doing so.

Now, it is late and I am tired, so please don't take any offense to this:
You're coming off of a worn out Porter Cable and a Craftsman.   Any Festool you pickup is going to seem almost surreal.  there aren't any close comparisons, besides the fact they're all called "Sanders" 

I don't know what your intended use is; or your intent, aside from your range of grits, so I wouldn't jump to anything conclusive.

I use an RO90, an RO125, an LS130 and a RAS115.
I'm a Professional user, and I depend on these tools for my livelihood.   while I'm working hard to add a couple more Festool sanders to my arsenal,  I can easily tackle any stair, millwork, furniture, cabinet as well as a myriad of other tasks I often encounter (from composites to metals to plastics and even automotive)  quite successfully.

If I had to pick only 1,  -the RO90 is clearly the most versatile

and while I hear you about the finishing sander needs, you're also talking about using 100g.   It sounds to me like you would most likely want the versatility of another ROTEX.  the 125 or the 150.      -I LOVE my RO125,  as I sand from 80g through 150g/220g  for most of my products,  and beyond that I am either taking the parts to the Finisher,  or I am setting up to finish.  sanding beyond 150-180 causes anomalies in the finish,  and once the wash coat goes on,  I'm just knocking the "Crunchies" off with a sponge... 

I suspect you are wanting to get rid of those tiny scratch circles caused by your PC and Craftsman sanders.
Using proper dust extraction and the right abrasive will solve that as soon as you're driving a Festool.

With Staircases,  EVERYTHING is under scrutiny.  -they're most often the focal point to begin with,  they're really expensive,  and everyone that passes through puts every part under the proverbial microscope.
I used to have a lot of problems with those 'sanding-pecker-tracks' that inferior sanders always leave.  that and the fact that I tried getting into corners with a Fein MultiMaster  (befitting they are now being sold at the big orange box, but I digress...)
this always caused damage, and I always had to go back and hand sand. 
That nonsense is now a thing of the past,  and while it seems like those quotes to the rhetoric of "Festool Sanders actually make sanding enjoyable"  are actually TRUE for anyone who has gone through years of not only hating sanding,  but LOATHING having to fix the damage caused by doing something they already despise...   insult to injury as it's called. 
but with these little gems,  it's an altogether different experience.
and it will put a smile on your face 

You're in NJ, right?      go here: http://www.festoolusa.com/where-to-buy/dealer-locator.html  put in your zip code, and pick out some dealers in your area.  I  find 5 of them within a 15 mile radius of Newark,  so  -you got it good!   the closest (only) one to me is an hour away 
-go check 'em out.  take some samples of you work with you and try them out.
you'll know which is right for you.
and remember, if after a couple weeks you find you've regret,  you can return it (under the 30day buy and try deal-e-o)


OH,  and FYI, I have used "Diablo" abrasives on my RO125 when I ran out of 5" Rubin,  and while the extraction wasn't as good, I still had far better extraction than anything else I've ever used with a shop vac.

Do you own a dust extractor that can be used with a Festool sander?

You won't find a bigger fan of the ETS 125 than me but I will be the first to tell you that it unsuitable for sanding below 150 grit.

"Unsuitable" as in there are better options. If it works for you- fine- but if I am sanding below 180 or 220 I use my Rotex. It gets me to the finish line quicker.

I only use my ETS 125 for the most delicate work, such as finish sanding, or veneer sanding.

After more playing around, uh, experimenting, I have some results. These two pictures are side by side comparisons of the results obtained with the MultiMaster vs. RO 125 in random orbit mode. In both pictures the MM results are at the top end of the board, with the RO 125 at the bottom. The MM used the stock abrasives it came with. On the RO 125 I used Granat with the hard pad. The first picture is using 80 for both. The second is 120. I didn't bother with pictures for the 180 because I figured the camera might not be able to pick up enough detail; but the results were similar.




That settles it for me. I'm buying a RO 90 to add to my stable. For sanding, the MM is being relegated to "only when I'm desperate."

I'm using minwax pre-stain then colonial maple stain followed by the minwax fast drying poly in semi gloss. Three coats of the poly seems to work out fine with a light buffing between coats.
The pre-stain actually does seem to help keep the stain from blotching the maple.

I tested up to 220 but the stain wouldn't absorb into the wood all that well at 220 and came out way lighter then I wanted it. 150 and 180 looked very similar as I recall. The cabinets are already done and in place as well as all the drawers (no storage space for completed cabinets so I had to install them to get room to work on the rest) and they were done to 180. I don't want to alter the formula on the doors and make them darker then what is there already.

Good thought on the RS2, that's something to look into.
Thanks
-Jim

People tend to recommend the sanders that they own.  As Stairman said most Festool sanders will be a big upgrade from box store sanders.  Here is the thing, the sander is only part of the equation.  Without proper technique you will still have sanding problems even with Festools.

Rotex sanders are great tools, but I feel from my personal experience best suited to refinishing tasks.  Yes they can do just about anything, but rarely does that type of tool do the best job at everything.  Rotex sanders can be a good investment  because of their versatility, so many users own one.  If you own a RO150 you might not buy an ETS 150/5, and guess which sander you are going to recommend for just about any task?  Testing out different sanders and studying their recommended uses is a good start to getting the best sander for you.

HTC TOOLS Festool Sanding Pad Jet Stream

You will be blown away by the ETS125,  and there is no problem sanding down to 100g...    the guys who own a herd of these tools, and are used to the power and efficiency of the larger sanders, would say it is underpowered,  -everything is relative...
but there is NOTHING wrong with the ETS sander,  and considering you are leaning towards multiple sanders anyway, I think the ETS125 is a great 1st purchase.   -application specific, I still maintain the RS2 would be the ideal sander for you,  but you'll be doing more than just a set of cabinets,  you've made a solid choice.

as soon as you buy it, you're going to learn all about FESTOOL ROI,  and a RO90 purchase will likely follow very soon      --so be prepared

OK, I'm looking for q new sander BUT,  I have a Bosch 3725 DVS attached to my Festool mini 22 dust collection system and I use it to smooth finish timbers on new furniture after joining and planing the furniture pieces.  I'm curious as to what Festool sander would replace my Bosch?

If you went to the 150/x line I would offer my opinion:

Go got the 150/3.  Why?  It has a final better product due to its orbit.  But is it the fastest?  NO.  But you can go courser and get the benefit of the finer orbit and then advance up in grits.  I Use mine to death and smile every time.

Peter