powdajohn,Good guesses here, I had a somewhat similar problem, it was a transmission belt slipping case.
How did you resolve this problem? I don't know who can do this work for me, do I have to go to BMW dealer to get it done?
I was reading on other forum that I have to take my mini to the bmw dealer to get the adaptations reset for the transmission. Google (Auto gear shift in high revs - North American Motoring)
Any help would be highly appreciated especially if you've had the same issue and solved it somehow. Thanks