Well, I got a chance to do some work with the Mark Brown/Gunsite/Aimpoint setup and the flattop/reflex setup, today. Got a quick tutorial from our own Rifle Forum Moderator, Mykl.
Many have heard me say that I don't consider myself a very competent rifle shot. That's 'cuz I'm not. However, by the end of an hour, Mykl had me *consistently* hitting short steel poppers at 300 yards from the prone, with *both* rifles! Am I beaming?
Back to the guns...I found the reflex quicker in acquisition and a bit easier, as it just has to be on the target...not lined up with the front sight. OTOH, absent flip up iron sights, when the Reflex goes down, you might as well hip fire. The Aimpoint is dependent on batteries, but at least has redundnt iron sights, as Hilton has pointed out.
I am told by some that the Reflex is rather fragile compared to the Aimpoint. Suggestions in helping me decide which way to go with a CAR-15 are greatly appreciated.