I did not have the opportunity to try the X5M but did have the chance to try an X6M and not impressed at all, RWD would have made me happier. Have you tried a 550 rwd? That thing with the traction and stability off still had a tonne of traction and no drama.
BMW 325I E30 Chumpcar Race Car
BMW 540iT M-Sport (New Family Hauler)
BMW 135i Msport Daily/track toy