I have heard good things about the springs.... 6-pak shocks, not as much.
I was down between Synergy, Metalcloak and Evo MFG when I changed out my JKU springs. I went with Evo and couldnt be happier. I installed Sumo Spring bumpstops with them and it made a HUGE improvement in ride quality offroad from my AEV springs.... adding Falcon 3.3s a few months later made it even better.