I have Dinan Stg. 3, and I like it pretty much. It does improve the handling a lot; however, the car is still sitting too high, and I also want a firmer ride. Believe it or not, the ride is pretty comfortable even with stg. 3.
I also had a chance to ride in a M5 with KW suspension, and the ride was a little bit bumpy to me. Would you consider using H&R coilover?