Congrats on the new car. It's compelling to me as a big fan and owner of an M3. I oogle these cars extensively when I catch one in a parking lot somewhere.
However, on the warranty side:
- Never tell any shop you drive on the track. Keep it simple.
- Both cars are officially encourgaed to be used in NON-COMPETITIVE/NON-TIMED track events and warranty should not be a problem in either case. Again dealers vary a lot on this so refer back to point 1.
- Legally, on paper, which is what ultimately matters, there is no substantial difference in the warranties between the two cars. I think you have more of perceived/practical advantage.