Larger disc will generally have better thermal management. However, just as important is the material the discs are made of...not all metal is the same or equal.
Brembo and AP have their own special formulas that are both track and street proven. Guess you will have to see how these hold up...better then some other cases we have found on the internet.
http://forums.bimmerforums.com/forum...=Racing+Brakes
Im a little surprised that this issue got glanced over and everyone shifted their attention to weight, clever tactics by some.