Fear of the ATF, and legal liability in general, is a powerful thing. Based on VTD's post, it appears that Armalite's email to me this Monday was a stock "civilian" answer to my question. I can only guess that Armalite won't sell its pre-ban mid-length configuration to civilians because of perceived legal exposure. Nothing else makes sense.
I'd go w/ a 14.5" setup in a heartbeat if the ballistic performance didn't differ so dramatically from the 16" setup at reasonable encounter ranges. (I'm an M1A shooter to this point, so I prefer to have some distance ability w/ reliable ballistic performance. Also, I'll be using an ACOG special forces optic, so "reaching out" a little is definitely on the menu.) The CAR 16" setup just doesn't look balanced to me. Also, based on my understanding of the AR operating system, moving the gas port even two inches closer to the muzzle should have a significantly positive affect on system pressurization, and hence reliability. (Armalite also confirmed this to me.)
For what it's worth.