I'm not an M3 owner (yet - hopefully this summer) but I was reading this thread and wanted to comment on the cross drilled rotors. Apparently many people had problems with cracking when the holes were actually DRILLED into the rotors therefore weakening the structure. The better "cross-drilled" rotors from what I am told are actually forged with the holes in them making one solid structure less prone to metal fatigue.
I was looking at the PDF file on the competition package and they said that the cross-drilled may make more noise than the regular rotors - is that the case? I personally think they look cool (and are almost 1" bigger) but I'm a big fan of symmetry. If they were cross-drilled in both the front AND the back I would like it better.
The other concern of mine is that performance brakes are usually meant for the track and do not necessarily perform the same way. My friend put performance pads and power slot rotors on his car and stated that they did not really start grabbing until they heated up and almost caused an accident when pulling out of a parking spot. Not to say that the BMW brakes would be the same as those.