No reason not to use P500S, as long as throttle and rpm restrictions are met, during the break in period.you are in the break in phase my friend.
In short you are stuck in P400 and the car is limited to 6k rpm's so you don't do any damage before the break in is complete. You should be able to make the shifts quicker via idrive or just push the shift button next to the gear shift.
I felt the exact same thing when switching from my M3 to my M6...even after the break-in....these cars just drive totally different...I have only 500 miles on my M6.Can not go over 6000 RPM yet. Gear changes feel a lot slower and softer than in M3. Is trans. protected during brake in?