I've been well satisfied with my 512. It has served me well in its role as a patrol rifle optic. I bought it over the Aimpoint because it was about $100 cheaper and came with its own integral mount. (If I'd known then how much money would be tied up in this gun, I probably would've just bought the Aimpoint LOL.)
No, it doesn't have quite the durability of the Aimpoint, nor the extremely long battery life. The latter, however, is easily solved by changing batteries on a regular basis. I normally change mine once a month or at every range trip. I throw the used batteries in a ziplock bag and use them for all the mini-maglites I have laying around, or TV remotes.
The circle and dot reticle on the EOTech looks weird at first; it appears "pixellated." Once you have the intensity properly adjusted for ambient light conditions, however, it will appear sharper. The one-MOA dot is pretty darn accurate at 0-100 yards.
I have mine on an absolute witness with my irons (both front and back Troy flip ups). The sight picture didn't appear cluttered, though, when it was mounted on an upper with a standard front sight base and rear BUIS.