The brakes will be fine on the street.
On the track the problem with the BMW brakes is not the unit itself. I know of many racers that use the stock caliper with good results. The problem is a lack of airflow into the brakes. As a result they get far too hot and fade pads, boil fluid, and wear rotors very quickly.
My last trip to the track in my e46 was to Laguna Seca, its a hard track for brakes. Still I destroyed two sets of front pads and a set of rotors in one weekend. Put new rotors on Friday, another set Monday.
With proper ducting of air to the rotors, they actually hold up very well. Still, I prefer the feel of the AP Racing (front) and Brembo (rear) on my other car.