I have a 512 AA on my 308. My wife has a 552 AA on her M4gery. No problems at all, and we shoot every day. Yeah, batteries don't last 10,000 hrs like the Aimpoint. So what? 2 AA batteries are a helluvalot easier to find than those lithium thingies, and it's not like they take up a lot of space in the rucksack. I really like the Eotech's built in mount, I really like the ability to cowitness without having to buy some extra gadgets/spacers/special mounts. I really like the reticle. Precise enough to engage targets at well over 200 yds and the donut of death is big enough to do some really fast target aquisition. It all comes down to preference. I prefer the look and handling characteristics of the Eotech over any of the dot sights on the market.
It all comes down to the old Ford, Dodge, Chevy debate...same-same GI, buy what works for you.