I haven't seen the one you linked, so I cant comment there. I had an Aimpoint on an Ultimak rail on my Saiga, and it worked great.
The red dots are a great way to go as your eyes start to go. Ive been using them for about 20 years now, and have them on a number of guns.
If you have an astigmatism they can be a pain to use. You only have a few seconds before the dot gets washed out or turns in to a crescent moon shape.
I have an astigmatism, and I dont have any troubles with the dot. It does look a bit more like a little star than a true, circular dot, but it doesnt wash out, or look like a crescent.
I have noticed that the brighter I make the dot, the more distorted it seems to get, but its still very much a definite aiming point, and still very easy to shoot with. I think you just have to find the level that works best for you. I find if I want better precision, I do better turning the brightness down where I can just barely see it. The dot looks more like a dot, and it also looks smaller.
Maybe the astigmatism thing is a varying sort of thing too, depending on how bad your eyes are.