I just finished assembling a PSA lower with a Rock River lower parts kit and A2 buttstock. I also added an Ergo SureGrip, a Timney drop-in 4 lb trigger group, and a Magpul enhanced trigger guard. I think I'm gonna order a Rock River Predator Pursuit 20" upper for it.
I went with the Palmetto State Armory lower partly due to price, but mostly due to availability. This is the first lower i've assembled entirely and I didn't want to screw up with a really nice one. Conveniently, I think these are the only lowers that are available and shipping regularly at the moment. Had I known assembling a lower would be so easy, I probably would have just ordered a Rock River lower, but this whole thing was a learning experience so I won't nitpick.
Overall, from what I can see, the lower is good quality. There are no burrs or machining marks anywhere. The phosphate coating is perfect, with no chips or marks anywhere. The parts in the RRA kit fit perfectly - snug, but not too tight. These lowers look to be as good as DPMS, Del-Ton, or other similar brands. Durability will be the next test for this lower. I will post a range report as soon as I get the upper and put a few rounds through it.