I use both the
TS 55 and the
TS 75. I think they are both great saws and easier to use than the others I've used. I first used a circular saw about 40 years ago and nothing I've used compares to either of them, though I haven't handled the new generation of wannabes.
The TS 75 is heavier but not terribly, about 3.7 lbs. I have never thought of it as unwieldy (I'm about 5' - 11", 180#) and when it's in place sitting on the guide rail and ready to use, it's a breeze. I have said to many people that they could probably cut their car in half with the TS 75 and I think that might be true.
The way I see it, the TS 75 cost 25% more and that should be the starting basis of anyone's analysis of whether it is worth having, assuming they have a use for it. Obviously, the blades cost more also.
If you plan to use it in any way other than riding along a guide rail that is UNDERNEATH the saw, then the weight can really become an issue. I have both and have used the TS 55 UPSIDE DOWN and underneath eaves to cut slots for venting. I would not have wanted to use a heavier saw for that application.
I have also used both saws to cut thick hardwood and found both to work quite well. The TS 75 in thick work pieces is obviously going to go through easier.
I think if you cut sheet goods and make cabinets, use the TS 55 and if you make doors, beefy tables, or do other work requiring deep cuts, get the TS 75.
There is one more thing to consider and that is the length of guide rail. The TS 75 comes with a longer guide rail because it has a bigger base and if you use it, think about the guide rails differently.
Tom