I have the 3'' sport kit. I have no issues with the rear drive shaft, but the front one at the trans case is at a steep angle, I am thinking a new front drive shaft will be in the future.
The rear one is fine. And same as Jeff, I am running the rancho 9000's. The ride is great, I have had it off roading a few times. Rides and handles great. I have no issues with this system what so ever.