Originally Posted by badfish
Actually I was asking because I know the answer and it's doesn't quite align with what you are saying but it's depends how you word it. So I'm just waiting for the answer...
Not all rotors will work with all calipers obviously, so as I said, I don't know the number of matching permutations that are appropiate for the M3. If you simply count the number of different types of discs that are being offered for instance, Brembo seems to have more. If you share what you know, that would be informative.