My greycasts have taken a slight greenish tinge after some wear... but I've seen selvedge... quality of the selvedge denim is probably slightly better... but the wear on the greys look wayyyy cooler than DS.
In all honesty.. it all goes with how ur gonna wear em, and whether ur preferred fit have em both, and ur budget. I dont know if RR comes in DG, but I'm pretty sure SJs come in them... As for DS, i think its only RR and SS. Not too sure. Also, selvedge is about AUD$80-100 more expensive.
Its a weigh out. I'm happy with my SJDGs though... and they're really starting to get comfy now.