I've got the R's so not a direct comparison, but they're fine after 8 months of use. They were a bit sticky at first, but I was told to use ptfe spray on the stanchions, put on with a rag, and now I've got them set up right (or seemingly anyway) they're fine. Done a couple of services too, and all's ok. The only problem I've had is sometimes the valve seems to leak if I reduce the pressure in them, but a couple of pumps back up seems to sort it, and they're not amazing on buzzy stuff, like tractor tyre prints. I'm not heavy, but they've had quite a lot of use.
I think there was a Bikeradar review which suggested the RC's weren't worth the extra money over the R's though.