i use my moonroof pretty often now .... but if i got an m3, i'd go for the CF roof... after all, no other mass produced car comes with a CF roof from the factory... the only other mass produced car with a cf rood is the M6 .... so you wont be seeing a lot of cars on the street with a CF roof. it's going to be something special.
Current: 2013 F10 M5 & 2013 GLK350
997.1 GT3RS (gone)
2009 WRX STI (gone)
e92 M3 (gone)