I'm off to shoot my new one soon, I got the HK style sights for it. They look nice, and sit lower. No cowitness with a red dot I had laying around, but since I was using that for a 9mm AR anyway, not a big deal.
My main suggestion for this gun is to take it apart and work the parts in a bit. The bottom mag release is a pain at first, but after working it over and over while watching TV, it's much better. The safety is also breaking in much better. My trigger isn't too bad, and I'm not that trigger sensitive, but it has improved with a bit of dry fire. The APX pistol was the same way, the trigger breaks in as does the disassembly latch with some working, no need for filing or stuff.
That and the bolt handle extension is the main thing.
I'm also bored and have extra kydex, so I'm going to cut out a cover for the offside ejection port, in case I use with a silencer it may reduce blowback and it's easy enough.