Let me tell you something about lowers...
Do all the pins fit? Yes? Your lower is good to go. Whichever you get. Personally, I'd get the $100 PSA MOE lower build kit. Hell, the pistol grip that comes with it is $25 bucks and they have free shipping right now on the PSA website. That's a damned good deal. Who cares if it's FN or not? Everything plugs in and works as it should without falling out.
As for PSA in general...
I've built four ARs from them, two carbines, one mid-length and one 20" A4 clone. I've got a 10.5" upper coming to do a pistol build. I put 10k rounds of .223 through all four, most of that through my latest carbine. Never had a malfunction EXCEPT on the 20" and that was just because it was my first lower and I put it together wrong. They're legit. Invest in their premium BCG or a BCM BCG and it's all good.
As for PSA Blems...
My current carbine is a 16" M4 that I built with a BCM BCG and all blemished parts. The "blem" on the lower is the anondizing inside the trigger guard is spotty looking, like the spots are thicker than the rest of the finish. The upper is a blemished upper and it has just a few noticeable tool marks on the inside of the receiver. Not rough or anything, just obvious. That's it. I've ran about 4k through this one carbine and for the first 3k I didn't even lube it out of the box or clean it. I've had zero problems with any of their "blems" because they're simple cosmetic defects, nothing like hairline cracks on the front of the receiver or something.
