Incidentally yesterday I had an opportunity to shoot ACOG.
This was the ACOG with the crossairs reticle and BDC hashmarks.
It was mounted on an Army issue M4A1 Carbine shooting M855A1 ammunition.
We did mostly updrills and other reflexive fire drills.
I noticed I was much slower with the ACOG than in the second half of the day when I switched to rifle mounted with the Aimpoint M68CCO (a very close military cousin of Aimpoint sights such as the Aimpoint PRO and Aimpoint Comp2 which IMO are simply civilian market versions of the M68).
I think the reticle and the smaller field of view played a major role here and in general the ACOG did not perform well for me (for short range reflexive fire )
Prism sights in general are very forgiving of aging or otherwise flawed eyes and the ACOG has a wide military fan base because of its value in longer range engagements in Afghanistan and elsewhere as its magnification made it superior to iron rights and Aimpoints in that situation.
But a) those folks did not have to cough up $1100+ for the ACOG and b) back then there wasnt much else out for the tactical prism sights.
Will the Primary Arms GLX 2x, or any other Prism sight work as well for sub 50 yard engagements (an important engagement distance IMO) as say an EOtech ?
But i know a lot of folks prefer/need a prismatic either due to eyesight issues or engagement distances ....
...and I believe due to the clever reticle, clear glass and wider field of view, they will be able to make this prismatic work well at shorter ranges too.