I know this is old, but bumping this up to share my experience. I replaced the stock shocks with the bilstein 5100's. Initial impression is a more planted feel, a little stiffer than stock. Over larger bumps and g out style bumps, the 5100's shine. Stick 10k behind the truck and they shine even brighter. The bilstein seems to fall short on small to medium chatter, which is where most of my driving is.
I switched them out for the rancho rs9000xl recently. Out of the box I grabbed the shock and I could actually compress it..... which had me a little worried. I slapped them on and the first thing I noticed was that the rear of my truck sits about 1/2" lower with the ranchos, just because the bilsteins had such a hard rebound pressure. Driving is very nice with the ranchos. All the small to medium chatter is soaked up instead of transferring straight to my spine. It does have a little more bounce on larger bumps, but not bad at all.
I prefer the rancho ride by far in comparison to the bilstein. We'll see how they hold up. I followed others advice and greased behind the adjuster knob before I put them on. Hope this helps someone on the fence.