That is why I decided to buy the 4WD Hardware (BDS) kit. I didn't want to worry about the springs sagging. I've done quiet a bit of reading and decided that you can't have your cake and eat it to. You either get a less expensive lift that will ride stiff but probably won't ever sag, or you spend a little more and get a better ride that articulates better for rock climbing but chance loosing and inch or two over time (faster if you add heavier bumpers, winch, hard top, etc.).
My ride is rough, but I'm sure it will loosen up a little after time. Also, I plan on better shocks in the not to distant future too. I may go with the Rancho 9000's.
2004 Rubicon, 6" lift, 35s, winch, hard top, full doors, bumpers, tire carrier and rock sliders.