It might run a little cooler,but isnt most of it cosmetic if it uses the same caliper?
Not necessarily. Even with the same caliper, I believe since the rotor is larger, you're getting more leverage than with the smaller rotor. When I had my WRX, one of the upgrades was to use the caliper bracket and rotor from a certain model year Legacy but still retaining the original caliper. I noticed a definite difference in braking...instead of the nose diving, the whole car kind of just sat down.
Performance White 2011 GT Premium, Brembos, 3.73 gears
Hushpower axlebacks, FRPP P springs, Barton shifter bracket, Barton white shift knob, CHE lower control arms, CHE adjustable panhard bar.