I have one PSA rifle, with a spec sheet identical to a Colt 6920.
I also have a Colt 6920. If you took the labels off of them, I wouldn't be able to tell a difference. I don't pound on them hard in terms of round count; maybe if I did, some difference would show up; I don't know. But it seems like a very good rifle to me.
I have tried to find this rifle on the PSA website a few times since, and it does not appear to be there.
They also seem to have a lot of "budget" materials that go into a lot of their rifles, especially the super low price point ones. What you get is very much variable from day to day and build to build. As long as you know what specs matter to you and why, hopefully you are getting a good deal.
So I think you can do well buying parts from them as long as you know exactly what you are getting, but be aware they put a lot of non milspec stuff into some of their lower end builds, I assume to get the price down.
The key components as far as I'm concerned is everything that is inline with the bore: Buffer tube, BCG, barrel. You can go cheap on everything else and still have a good reliable rifle.