I'm not sure if the sonicrafter has been covered before, I just joined and this is my first post. 

Let me start with a caveat.  I have never owned, nor used in the field, a fein multimaster.  That should be known because I would really like to compare the rockwell with the original, however, not really qualified to do that.  I have used the mm in a tool store display.  That's it.  Also, I own a small residential remodeling company in metropolitan NY.  I make my living with my tools, so my perspective is shaped by that fact.  Any professional who reads tool reviews by people who build for a hobby will certainly understand what I mean.  This is not judgemental, but a realization that all decisions that we contractors make are based on a cost/benefit analysis.  If your are doing this as a hobby it may benefit you to look at my review in that light.  Oh, and I had a small technical problem at the end of this post so my formatting is inconsistent.  I apologize.
The good
Well, first off is the price.  At $180.00 bucks for the complete kit you can't go wrong.  It has almost everything you would get with the fein, except a few key accessories.  More about that later. 
Durability.  This tool has the trademark colors and feel somewhat like porter cable.  No frills, bullet proof construction is the key here.  Definitely a tool you can use on a professional job site.  So far the cutters  and accessories seem to hold up fairly well.
Power.  At 2.3amps and up to 20,000 opm this thing has no problem cutting through anything I ask.  (with the proper blade).  It also allows you to dial down the speed with a 6 position speed control.  Maybe it's just my more is better personality, but I haven't found a need for anything other than full speed.

The Bad
Mounting Chuck.  Unlike the excellent quick release mount on the multi master the sc uses an allen head screw and washer.  While this is not as fast and convenient as the mm system it does do an adequate job of securing the cutter.  They even give you an extra screw just in case you strip out the first one.
The case.  Also unlike the fien you don?t get a hard shelled case.  The cc comes in a soft side bag.  While I prefer the protection and organizing capabilities of fien?s  case, the soft side bag does prevent scratches if carelessly laid on a finished surface.  This is important in the residential kitchens I usually find myself in.  There is also a cheap plastic box to put accessories in, but I don?t expect it to last long.
Accessories.  While the deluxe kit is well equipped for the price, it is by no means complete.  Not only are there no profile sanding accessories included, but they are also unavailable at this time.  The same is to be said for the flush cutting half moon cutter (I?m not sure what the official name is).  This is the almost circular saw blade, with the recessed mounting hole that would lets say allow you to cut the  ?? face frame lip off of the side of a cabinet to be refaced (I currently use a bosch router connected to the ct22 with a pvc pipe contraption I made, more on this in a later post).  The chuck for the cc is a milled washer and screw over what looks like a hex head mount.  The blade has what I would describe as a 12 point hole.  This works just like a socket over a nut.  It gives a pretty good bite, and allows for offset angles, however, and I think this is on purpose, there is NO WAY you can put anyone?s blades on this machine.  (Anyone who can prove me wrong please comment, I would love to be able to put some MM accessories on this thing.) 

The bottom line.
If you are in the market for a multimaster, but don?t want to fork out the $400.00 and can live with some of the accessory limitations the Rockwell Sonicrafter may be the machine for you.  For detail sanding, scraping, plunge cutting and all sorts of tile rework and repairs you can?t go wrong.

frank-jan

thanks for the reply and the welcome

I'll have to experiment with the speed control