I have a 2011 535i xDrive with KW Variant 3 coilovers, installed by my BMW dealer about a year ago. I am absolutely delighted with the performance improvement over stock, and particularly over the H&R lowering springs I had previously put in. Handles the worst potholes without bottoming out, and never floats.
My KW kit did not have electronic damping control, so KW included a feedback loop wire to prevent the system from throwing EDC failure codes. That feature has proven to be less than optimal -- have had to repair the wiring on three corners so far.
Anyone who wants the H&R's PM me -- free, you pay shipping (from Toronto, Canada).