I just finished building the first of three SSA Gen II stripped lowers that I bought from AIM, and I think I actually like the SSA's finish better than my two Spike's.
I used a PSA parts kit, and everything went together with no issues at all.
I put a BCA upper on it, and it fit the SSA really well, with hardly any slop at all.
There was a small raised line above and behind the pistol grip. Since I prefer a grip that has an extension for the web of the hand, like a
Magpul MOE, and that type of grip covers that area on the lower, I didn't mind that at all. The original GI grip wouldn't cover it, but I don't think it would be a problem any way, because it wasn't sharp or irritating like flash would be. It really was barely even noticeable. I only mentioned this to be thorough, and that was the ONLY criticism I have of this lower at all!