Alright, I picked up my B&T APC9 and P26 polymer receivers from SymbolArts in South Ogden this morning and I am fairly happy with the work they did. The turn around was faster than what they quoted, the price was very good and the work itself appears to meet the NFA requirements compared to my other SBR's. The only critique that I have is that the spacing is better on the P26 than on the APC9, but the placement is better on the APC9 than on the P26. Again, for me the work is good, my weapons are tools and I don't care everything is perfect.
So if you are looking for top quality work, look elsewhere. If you want to spend as little as possible (about $13 for my two weapons) and Ogden isn't too far from you, then maybe check out SymbolArts.
I have two more weapons that I will have engraved here pretty soon, I will take them to other engravers fairly local to me to compare the work. I will update again when I get them back.