I have tracked my 330i many times. Both with stock compound, and more recently with the Carbo Tech pads.
Street: The stock brakes work great. I never encountered any fade, or noise. They wore amazingly well - given that I tend to use them! All four wore evenly. I have 90K's on the original rotors, including 20+ track days!
The Carbo Techs were not so nice on the street. They stop ok (not as well as stock) but really prefer getting really hot first. I found them to be quite loud - squealing in a very annoying kind of way. Also, I would definitely NOT use these in cold temperatures. It's worth the time to switch back to stocks for the street.
Track: The stock brakes worked quite well for me. With street tires, they were perfect (I could activate ABS at any speed on dry surface). For R-compound tires, I would say they are 8/10th what the Carbo Techs are. The only serious fault I found was in breaking for corner 5a at Mosport after I had moved to R-Compound tires. For those of you who have been on this track you will recognize this as the hardest breaking point. I found the stock pads did not give me enough force at this extreme. However, other than this, the stock pads performed well, AND they wore amazingly well (both pad and rotor!).
The Carbo Techs were a nice improvement over the stock breaks. The initial bite was better (although there are better aftermarket pads for this) and the fade encountered in 5a did not occur. I actually feel my eyeballs coming out of the sockets now!! However, these pads were definitely harder on my rotors. Probably during the street driving more than anything else - since they just couldn't heat up.
Conclusion (my own of course): For the street, the stock 330i (same as ci) pads are great. Don't touch it! For the track, after some experience, you will probably want to use a more aggressive compound. However, you will not likely reach that point until you have had a few years of experience AND have moved to R-Compound tires.