The TA11 series is the brightest (largest exit pupil, 10mm), and the most forgiving of eye placement and has the longest relief of all the ACOGs.
If you might ever use it on a 30cal, you really need the extra eye relief. I prefer the longer eye relief on the AR too just beacuse it's more relaxed and not so close, but on a 7.62 or heavier the longer relief is required.
I had a freind scarred badly this year by wearing his hunting scope. He was laying prone facing downhill, in snow and heavy clothes, and shooting uphill at a buck on another hill. He lost his shoulder weld due to angle and clothes and got slapped bad. Bloodied and shaken, he did get the buck!
The ACOG is much more forgiving than a standard hunting scope because it has a very shallow rounded edge, but I don't want it hitting me or anyone shooting my rifles for it's own sake and ours.
Hitting someones glasses might scratch it too, whcih would be horrible. I'd rather bleed myself!
The BAC red donut reticle is not as precise as other reticles due to it's curves and lack of angles. But for speed once you practice and think about the Binden Aiming technique enough and it becomes second nature it works very well. A chevron or other shape might work just as well for both eyes open as long as it is bright, but also be more precise with it's angle shaped pointer.
Hint: From my friend Mr Nash Coldiron (no fooling, thats his real birth name!)
For precise target shooting with an ACOG, cover the fiber optic with electrical tape [touching just enough to stick]
blocking ambient light from getting in, and causing the reticle to appear black, which looks sharper than a glowing color. ;-P
My two cents on ACOGs.
Nuts{WoC}