I deliberately waited until my dealer had a MINI One to try when road-testing the Cooper and seriously considered buying it. It was only the fact that the car insurance on the Cooper was better than I expected, and so affordable, that swayed the decision.
I enjoyed driving the MINI One a lot and would not feel it was inferior to the other MINIs at all.
If it suits your needs then thats all that matters.
Enjoy your MINI and the forum....