I had an '04 Disco and spent some time on the LR forums, while shopping for it, and after I bought it (I was considering the RR too). It seemed it was very hit-and-miss as far as failures, but when systems did fail, it was bad, and expensive. I can't remember if '04 is the newer RR body style, or if that was '05 (I think '04 was the new gen for the RR), but I know there have been plenty of people left riding on bump stops because of the air suspension system failure. Other odd bits like cracked headers, cracked heads, and electrical issues were on peoples' lists IIRC. Many people have never had problems, and others have been left by the side of the road multiple times.
Honestly, though, my wallet would feel more comfortable owning the RR out of warranty than my 335. My Disco had almost zero problems, and was by far the best truck I've ever owned or used. The only issue I had was with gas mileage (13mpg combined), and a failed cargo door lock actuator. And, man, did that truck own shit off-roading, too. LR builds impressive vehicles. They don't seem as much "utility" focused as they used to be, but they still have that personality you can't get elsewhere.