I also have a fancy for one of these for my next car, only real info i can add from what i have dug up is they go through clutches quite regular, anything from 40-60K will usually need replacing which plays on my mind a bit.
Also had some negative comments for daily town driving, aparantly the gearbox isnt great at low speeds etc, but that may be a personal opinion, im still gonna go have a couple of test drives before ''im out'' on the M5.
Apart from that its been one of my dream cars and i fancy doing it when i get home from working abroad.