Here's another one to add to the list. My RT was in for a 6K service at my BMW dealer. During the service the technician discovered that the final drive was grinding. Looks like a replacement is the next event. The folks at the dealer advised me not to ride it so I had an ignominious ride home on a beautiful day in a rental car.
I had purchased an extended warranty a couple of years ago, and so the Service Mgr. is working with that company to get authorization to replace the unit. I think I'll be OK, money-wise. FWIW, this RT had been serviced strictly by BMW dealers since new.