Those who have them, love them. They are not priced the same as FF2s though and not exactly budget friendly and hence many just settle for the FF. For the 6thgen only the KWv1 is offered though which suck a bit as they are not individually height adjustable but use the same lowering method as tein and only offer lowering of 1.4" to 2.5". At the same time they are not meant for just dumping your car. They do have a lifetime warranty though unlike Tein and have progressive springs in the front and 230lb/in or 4.1kg/mm in the rear. http://www.kw-store.com/products/kw-coilover-kit-v1-95.html
I thought about them after I sold the AMRs since Mr.Andy Reyes doesn't know how to handle bussines...and the only thing that made me go to Tein SS versus the KWv1 was mainly price($950 vs ~$1400-1500) and the fact that none of the distributors were willing to mark their value down so i'd be hit with crazy duties/taxes.