So I can speak to the FM9. I shoot USPSA with a QC10 lower with Geissele trigger and FM9 16" upper. Optic is a Holosun 510c and Crimson Trace CMR-206 for close in.
I also shoot GADPA with a 8.5" complete FM9 "pistol" with Primary Arms red dot and Geissele trigger. The FM Products billet lower is the best one on the market, imho. It is so reliable Primary Weapons Systems contracted FM Products to make their PCC.
Both guns shoot super awesome, more accurate than I am.
Awesome, I ordered one yesterday.