I have a 4x32 USMC A4 spec model on my 20" M16 clone. I haven't had it all that long and really haven't got to use it in a quick shooting scenario yet, but I have a plan to evaluate it.
I'm going to use it in a 3-gun match at some point, both eyes open, as a red dot at close range.
1) bring rifle on close range target
2) see the chevron, just as a "dot" through my strong side eye. the target through this eye will be blurred and not really visible.
3) see the target through my weak side eye (not looking through the scope). Your brain will superimpose the two images like usual, and the "dot" will appear close enough to on target for the purposes of shooting quickly that close up.
4) Shoot.
For more precise shots further out, of course you just look through the scope and use the recticle as intended.
I doubt it will ever be as fast as a true red dot in this scenario (due to the eye relief, field of view, etc) , but I have a theory that it can be more flexible at close range than it often gets credit for, even without the little "doctor" sight on top. And of course, it is a fine scope at medium range.
So is it worth the money? Well, depends I guess. I used to resist spending a lot of money on optics, but really, you can't hit what you can't see. To me, its worth it if it does its job to perfection and that is what you want.
The ACOG is very tough, and also has the advantage of not having any batteries to die, as it uses tritium to give the recticle a little illumination in the dark, and collects ambient light to scale the brightness to available lighting conditions.