Most red dot style optics do have adjustable brightness, and it is definitely needed. A key point to look for in your search is the size of the "dot" it uses. A 3MOA dot covers 3" at 100 yards, but 9" at 300 yards.
I've used a couple with larger 5"-6" dots and they were hard for me to be at all accurate with at longer distances. The Eotech is a fantastic unit, and the holosight is the same thing in a case that isn't as tough - meaning it will work great but don't drop it on a rock.
I would suggest getting a unit that has no larger than a 3MOA dot, and most of the holosight/eotech units are 1MOA these days which is great. One feature they have that many cheaper units don't have is an automatic shut-off after 8 hours, which is probably going to save your batteries at least once in the time you own it. They also flash at startup to let you know when the battery is getting low.
Other than price, the only complaint I've had with the eotech was how high it sits on the rail. With many rifles it is hard to have a cheek weld when using them, but it is also less important due to very little parallax. The holosight is now available in a low profile version which should minimize that problem.
The red dot style optic is super fast, but without magnification it can be just as difficult to shoot accurately at longer distances as irons sights are. If your eyes are able to get a good sight picture with irons at your intended hunting distances, then you will love the red dot for giving you the same accuracy in a fraction of the time.