I did the M Perf setup, but I own a RWD 335i.
It's a 20mm drop, real subtle.
Handling is amazing compared to stock, about 20% less firm than an M, and if you've driven an Mitsu Evo, about 25% less form than that. Very daily drive able (my wife hasn't even noticed).
The car is more planted and stable, has much more manageable understeer, and is sharper than the base suspension (by a 2-fold margin...the kit was designed with M engineers so I think they got it close to what is acceptable outside of an M car).
Cons: you'll notice road imperfections more.
2012 335i Mineral Gray
JB4|M Performance Exhaust/Brakes/Suspension/LSD|Bav Stage 1/AMP||ER CP/IC/DP | Dinan CAI/N55 PWG BIG TURBO|BMWF30.com