Jay - I understand your situation. We've had our 15-22 for almost a year now, and have had a "cheap" ($120 at local gun shop) Osprey Holo sight for that. For the 15-22 the Osprey is great, 4 different rectals, RED or GREEN, my son just loves it. It was our first experience with a Red Dot or Holo and we are very happy with it.
Then I got the M&P15OR. I went to the same local dealer who I trust and asked him about using the Osprey Holo on a 5.56, would it hold up long term. He said he had several customers that did just that, and he had no reported issues. He also had the EOTech XPS2 that I "lusted" for. I'd wanted a AR15 with EOTech for years, so against his advice I got the EOTech from him. The boys aren't that impressed as it is only RED and only the single rectal. I like it because, well I like it.
The XPS2-0 turns it self off after 4 or 8 hours (depending on which button you turn it on with), so it would NOT be always ON as the above mentioned Aimpoint. I don't consider that an issue, but I have a Sig P226 9mm that is my primary home defense weapon.
If used as a battle or defense weapon, I consider BUS required. The battery will die in everything at some point. Some of these give good advanced warning of "end of battery life approaching", but I wouldn't ever bet my life on a battery if I don't have to.
I think the Holo sights make the ultimate close quarters combat sight. Both eyes open is a huge advantage in that environment.
If target shooting is the main use, then well it is >$400 for an unmagnified optic. For such a short barrel (to me who has mainly owned hunting rifles for the past 40 years) I am pleased/surprised by my AR15's accuracy. And am finding I like shooting it >100 yards. At that distance, with my poor eyes, I need magnification. I intend to get a magnifier next year for "long range" days

. If I was to get the EOTech one (which I have not decided yet) I'd have about $1000 in optics. We are passed some really, really nice scopes by that point (to me we were at $400). But the joy of assaulting those nasty beer cans at 40 yards with both eyes open is worth a lot to me.
