From what I've heard ... and these are rumours I read from someone on a belgian carforum (he got it from his dealer). All 335i/d's are now fitted with the M sports suspension as standard. The difference:
The normal sports suspension is 100% stiff, where the M sports is more comfortable the first 25%. So I reckon the M sports is the best suspension.
I have the same fear .. I have ordered my 335d coupé with the M package, and upgraded to 19" wheels. I don't want uber-stiffness. First thing I will do is replace the run-flat tyres with normal tyres (goodyear f1 or bridgestone potenza's).
Some people even say: run flat + 17" == normal tyres + 19"