we own both (06 M5 and 07 sport gt)
feel free to PM me with some questions...

Evo magazine in the UK quote the QP as being faster around their track than an m5, not bad for a car with over 100hp less.

IMO both are nice but the QP is the ultimate, the m5 may be good, but at the end of the day, with all due respect, it is just a top of the range 5 series, the QP is never going to be confused with a family car.

I did take the trade. It was done back in december.

Maserati are hot