It might just be the random number god at work, but I think the 1000's/500's are much more common in the upper-level raids. Was shrouding the other day and across 5 or 6 runs I pulled 4 of the 1000's, 2 or 3 500's and a mess of 150's/50's. I'm actually starting to think the higher level stuff is better for renown that low-level chest filled stuff- did the issue with all the lowbie stuff being better for renown get fixed while I wasn't looking or something?