I have used a RRA parts kit, it was fantastic and went together as expected.
I bought a DPMS parts kit, and the first roll pin punch I tried to assemble into a bushy lower for the trigger guard was oversized and wouldn't collapse properly, so I had to back it out.
Side by side, both kits wery fully functional, but I thought the RRA kit had nicer finishing and more attention to detail -- sometimes, a shortcut was taken on the DPMS kit, like drilling a hole entirely through the takedown pin instead of drilling in just enough to make an indent for the detent to sit in, and the magazine button had less ridges cut into the face, making it feel not quite as nice to me. Again, NOT a functional difference, just a manufacturing simplicity which they use to pass the savings on to you. Personally I prefer the higher fit and finish but YMMV.
I have never heard of a problem with any name brand kit. I always hear about problems from non name-brand kits from EBay or other dubious sources.
A ended up buying a Bushmaster kit for that Bushy lower, the roll pins were better. Wonderful kit. Has a plastic trigger guard, where the others had aluminum. I think that's fine, maybe even better, an impact on it will not bend it to block trigger travel in the field.
-Dan