Pat Rogers favors the Aimpoint Comp M2 and has a great deal of experience with these sorts of sights under difficult conditions. The single-plane, parallax-free nature of the sight facilitates use in the various improvised and/or non-traditional shooting positions that can be helpful in utilizing cover.
Being a believer in Murphy, I think the rifle should have backup iron sights. The optic should also be quick-detachable in case the lens' become muddied, fogged, or broken. That is, one should not count on being able to use his backup iron sights through the optic's tube.
It is counterproductive to just decry a lack of training and skill when there are inexpensive "hardware" fixes that will allow more of one's people to hit effectively. If they can hit effectively, then they will enagage targets, rather than just hunkering down.
As to the battery issue (Rogers terms it "batteryphobia"); there are batteries in much of the stuff that the modern soldier must rely on...communications, GPS units, night vision devices, his vehicles, and so forth. If we are postulating a post-apocalyptic "Mad Max" kind of scenario, then I share your concern about batteries.
Rosco