The thing with the Mini is because its so compact, there is no space to work on it.
If you want to change a clutch, you will need to strip out most of the front, including the bumpers, coolers ect to get the gearbox out....
Also they really are two differant classes of cars, passanger space is non existant in the mini, if you can deal with that though, the steering on a normal couper never mind the S is some of the best I have ever felt.
Fun and enjoyment, with perhaps a bit more risk, mini ftw
Also, power to weight, the mini is going to perform far better then the E90
But the E90 is actually a more comfortable ride, cheeper on maintance, and will keep its value better (in comparison)....
Now if you were talking about a 330 or a 335, this would of been a totally differant argument.