I have had 2 trucks with 9000s on them. No problems with either, put 150K on set on my 96 and have about 60k on the 01 with no problems.
But...
I think that the best set up is Rancho's on the back, for adjustiblity. And Bilsteins on the front. I never adjust the fronts and it is actually a pain to adjust the fronts. Also I mounted the rears with the knobs both pointing to the rear. That I think protects the knob from alot of things. Also with Ranchos just on the rear, if you have a problem they are a cinch to replace back there, ten minutes tops. I can put up with some quality issues to have a better unloaded ride and be able to load up the Slide in and crank up the dampening. But as I said no issues here.
The 03 is getting Ranchos in the rear soon, and the Bilsteins up front when I have the dough.
---DOug