Ive had the RCX 6" suspension lift on for 20k miles. No issues or complaints here. I also have 2 buddies with '11 CC Sport 4x4s going with the same lift this month.
The RCX kit rides identical to stock. The kit is very strong and well made. I use mine to offroad and beatup as well to hunt. Ive thrashed it pretty good, slamming the front end into ditches and and ruts and what have you. Its still holding up as it was new. Not to mention you get a Lifetime Warranty.
Compared to the rest of the 6" lifts it also gives the most ground clearance, both the crossmembers and the slidplate by a couple inches. If you want to add the Bilstiens it also provides the most lift when combined together.