I can't really help tbh as I am trying to decide exactly what I want.
It's a bit of a no brainer when the m5 is actually cheaper to buy imo.
The wheels are just preference, the standards make the car look a little under wheeled but then the tyres will be cheaper to replace and ride is bound to be better.
Have a read though this thread
http://www.pistonheads.com/gassing/t...%3F&mid=113183