I keep hearing rave reviews for the 511's, they are apparently gaining popularity.
I usually wear BDU pattern trousers for outdoor recreation, either cotton weave khaki or 3 color desert 50/50. The challenge with BDU pants is finding a manufacturer that makes them properly, most cheat on the fabric and short you either in the seat, thighs or groin.
I've had good luck though with Shomer Tec in Washington state. If you like the RR pants I'd say stick with them, you're probably in good company. Thinking of getting a few pair myself.