To me, mushy does not equal lightness... 30g RF are light and has lower tactility, but the characteristics are similar in that the key press is smooth, tactility is soft but present, and the landing is firm. The common mushy feeling associated with lower quality rubber domes is not there at all.
Except that's what Topre have done: the 35 g switches are mushy instead of being light. The problem with many rubber dome boards is that they have a very poorly-defined tactile point, to the extent that they can be mistaken for being linear. If you push the switch lightly, it just squishes without a sharp tactile bump. I think this is what's given rubber domes such a bad name for most people. The AppleDesign Keyboard is one of these squishy boards.
That's what's happened to the Topre 35 g domes – they don't feel lighter, they're just not really tactile. The 45 g switches have a very sharp tactile point. However, for whatever reason it doesn't seem to matter if you weaken the outer keys, and I don't know how much worse it would be if the centre (45 g) domes were just as smooshy as the outer ones. 45 g Topre domes are exceptionally good.
I'd be intrigued to try an all 55 g board, as the 55 g dome feels almost as stiff as blue Alps. (Vintage blue Alps is only something like a 45–50 g spring, but it does have a very sharp, strong tactile point.)