As the originator of this thread, I can confirm two things.
1) MINI's don't tramline on their own. We bought a MINI that had been well maintaind instead of that POS at the dealer (with 50k miles less and some good aftermarket parts for $5K less!) and it has never wandered on the roads.
2) The run flat tires are garbage! We're running Bridgestones non run flats and the car handles very well. I have told my wife and son that drive the car that they will get a lesson in how to use a plug kit and there is a cigarette lighter powered compressor in the car.

I agree withthe rest who said that the dealer was ripping you off on the DSC issue. The tire pressure monitor is actually a wheel revolution counter, not an actual pressure monitor. It calculates a loss of pressure if there is a loss in wheel diameter. It doesn't take much, and it has been relatively accurate the one time we had the tire monitor light come on.