Agreed, I always run 320's on track/race bikes. If for no other reason it's so much easier to take the calipers off for tire changes. There's also the (theoritical at least) reduction in gyroscopic force to aid in turning. For braking performance, I think the brake pads make much more of a difference than an extra 10mm of rotor diameter. I've ran HPK's and T-Drives on quite a few different bikes, and as far as function I've never noticed any difference at all other than what was noted about the T-Drives being noisier when pushing the bike around in the paddock. The HPK's are a little cheaper and depending on the bike color the gold rotor carriers look pretty cool IMO.