I impulse bought what was sold to me, and appeared to actually be, a NOS '27, and a used KAC Refurb PVS-30, with maybe mid 1700s FOM.
I preferred the 30 in every situation that I tired (limited, no shooting, but mounted to rifles with various scopes and to a and Leupy MK4 spotter, and under varying light conditions).
As far as "value", usually you have to pay factors for that last bit of performance, and I agree that the three '27s that you could buy for the same price could be better than one of either of what I mentioned.
No reason to get a 30 over the A2. A2 is easier (shorter reach to lever) to focus...which is the main complaint with the 30. Also a little shorter reach to the on/off/gain knob.
My understanding is KAC is utilizing high-spec Elbits (WP) these days.
Sure, used 27 is less $$, also larger footprint. Only you can decide what you want.