I have to squat in hard soled shoes. anything with cushion i feel unstable with heavy weight. i used to squat in chuck taylors or the flat soled Adidas.

I'm the same way...I prefer no shoes when I squat but if I do that every wk my arches start screaming...so I split it up about 50/50 these days, but probably a little more shoeless then not.
If I squat in any shoe with a thick cushion, especially a shox, I cannot for for the life of me keep my heels flat on the ground, which in turn will make you lean forward...not good.
The pair of shoes I do squat in are not comfortable for anything else. Their Nike's and the bottoms are very flat and brick hard...and I do mean very hard. I also really like doing lunges in these shoes...when I bought these a year ago, I know I looked like a tool trying them out. Most people just put a shoe on and walk around a bit to see if they like it...in this case, I actually lunged a few lunges across the store in them and did some boyweight squats to see how they felt. Looked like an idiot? Probably, but the point was to find the perfect shoe for legs, so who cares.
BTW, the right shoes are everything when doing legs!