Red dots have a few problems as mentioned and here is my take on it. The only time I really had a hard time seeing the dot was plinking during the summer during midday(July in Catskills). At this time of year here in the NE I have never had a problem as the sun is at a much lower angle in the sky. I have neverbeen unable to see the red dot during hunting season.
Some of the cheap dots have 4-6moa dot or larger for short range sighting. A few of the more expensive ones will have smaller dots availablethat are much more accurate. Nikon VSd has a 1MOA dot on theirs that is very accurate and aimpoint has a 2moa dot and 2x magnification. great sights and nothing is faster. When you go still hunting in heavy brush, nothing is better. As far as reliability,this is deer hunting. The batteries last for hundreds of hours, some like the aimpoint claim to last foryears. How hard is it to buy a new battery every year for 5 bucks? If red dots are good enough for the military I'm sure they are reliable enough for deerhunting. I have left them on for the whole deer season here(NY, 3-4 weeks, 20 days+-)and they were still working.
And I only use them for still hunting during the day. At dawn and dusk i'm usually staying in one place waiting with a scoped rifle. In low light dusk/dawn situations scopes are 100% better and gather much more light, they give you at least a half hour extra shooting time at each end of the day.Also I may bea little biased because the red dots are the only sights I can aim real quicklybecause my eyes are cross dominant and don't give me a problem when I aim fast usingone eye since they have almost no magnification. Hope this gives you some info. take care.