I had the RPS sprung hub with TRD(RPS) PP and ClutchMasters LF. Never had spring problems though, and it launched really nice, just didn't take all the tranny noise away. One side of the disk seemed to wear more than the other and I will talk to RPS about that but I took it out to redo the whole drivetrain(motor/single turbo/and all) and try out TRD's(Exedy) Twin sprung hub disk setup.
-I like trying different setups so I can recommend the right ones-
Anyone with RPS problems should always give them a call regardless of warranty, they're very customer oriented from what I've seen or heard.