Threads like these remind me of my 6960 CCU Upper score w/Centurion rail for $450-ish from Brownells a couple years ago… that was like, almost, free, IMO.
I almost bought a 6921 14.5" upper for $429, but then it needs a $350 Centurion rail, BCG, CH, etc… Thankfully they are out of stock now so I’m saved. 
I almost bought one of those 6921 uppers too but I just couldn’t quite justify it…especially when the ammo situation has forced me to sideline my ARs somewhat (I’ve had to pivot to AKs). Instead I saved like $160 and just bought a Colt 14.5” barrel with FSB at Arms Unlimited, and I can use the $160 for something else.