FWIW, I did my first track event last month. I had installed Pagid RS19s after reading comments on the board (thanks again to Lucid for the extensive DIY!). I did not turn my rotors as the car was new (3k miles) and the rotors had no signs of grooves. I did bed them in.
After about 60 laps (4 sessions x 15 laps per) around Laguna Seca I have to say that the M3's brakes are more than adequate and I don't see any need for a BBK. Also $750 for the pads is brutal but they worked flawlessly for me and I would highly recommend them. The only downsides are they squeak like hell on the street and generate a lot of dust.