Car has 29K miles, probably close to 5500 advanced/instructor track miles
PS: Mine leaks like everyone else's. I use the shop towel and zip tie and keep it topped up. It does not fail (cavitation) like it did on the E46. so I'm happy.
Brakes: With SRF and DTC70s, they hold up just fine in terms of fade. But I'm not doing anything more than 25-30min sessions. The behavior is inconsistent - sometimes the car is a bit unstable transitioning onto the brakes - like the back wants to step out (going into T1 at TWS CCW, or T15 CW), and other times the pedal stiffens up at odd times, especially when you are trying to modulate aggressively or need to reapply after a large bump (Going into T10 CCW or T3 CW). I don't think a BBK will address the issue, I think it's the electronic brake force distribution or the assist system itself.
Engine: Rock solid. Uses a 1/2 to 3/4 quart of oil every ~15K. I am having temps issues in 70+ ambient temps, but I do beat on the car pretty hard with DCT (drive near redline at all times). Turning the heater on helps. If you leave the A/C on it will ALWAYS go into limp mode in my experience....ask me how I know.
Diff: I can feel the diff shuddering/slipping under power pulling out of left corners, like T2 CCW at TWS. I would not be surprised if it fails.
Suspension: Clearly wearing out. Stock springs, it's getting bouncy - like not enough fast rebound in soft mode.
Bushings: Car feels looser than I remember it - but the alignment is holding. It could probably use new bushings where the highest lateral loads are transmitted into the chassis.