my first recomendation is to replace with factory bmw parts.
If you want to drop a few lbs, get the M5 euro spec rotors.
If the above does not satisfy your need to braking performance, upgrade the lines to SS braded teflon lines, and upgrade the pads to something more aggressive. There are several great posts on pad recomendation ( Use the search function).
If at this stage you are getting brake fade, you can upgrade your backing plates to Ti backing plates. ( motul 600 is a great fluid BTW)
Now if the above still cannot slow the beast down the way you want, then look into a BBK.
Now if you have the cash and simply want the best looking and performing brakes, go with a Stoptech or brembo BBK.
Edit note: THe brake pad sensors are not tricky in the slightest. If you have the correct pads, the sensor, which is a wire running through a rubber slug, simply pop into place at the rear of the pad.