Dude, welcome to the the AR-xx abyss
I know Aero well, they are milled ~75mi S of me & my LGS sells the snot out of them.
Tight tolorances & if I wasn’t such a Spikes Tactical billet lower whore, Aero would be on my short list of alternates.
Their upper & lowers are machined to the point it is like closing the door on a new Lexus.
Best analogy I can think of.
The AR abyss is a scary and expensive place!!
You make a good case for me to just get an aero upper and lower and skip the BCM and save the $350-400. I just keep reading that everyone prefers the BCM upper if you have the coin.
But...I did just find that a gun store on my way to the outer banks tomorrow may have a BCM Recce 16 in stock...may have to stop by tomorrow.