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.
Current: 2016 F80 M3 6-Speed | SO | AB XT1 | ZCP | M Performance Suspension | GC Camber Plates
Previous: 2009 E90 M3