you are absolutely right about the exit speed. I noticed a lot of understeer going into corners, and it made me shave off speed in order to make it to the apex. With the extra grip resulting from the wider tires upfront, i think this problem would be less noticeable if not absent.
Also i see pretty much every regular track attendee with square setup.
Mind you, I'm still in the process to get my square set, so take it for what it's worth-pure speculation.