The answer is easier for me. I don't have MDM. Consequently, it's always OFF at the track which suits me just fine. The car is extremely balanced, particularly with a square setup, and I feel that DSC OFF encourages smoother input.
2009 E90 M3 | SG | FR | 6Speed | Akrapovic Evo | JRZ RS1 | StopTech Trophy | Cantrell Brake Ducts