I'm in the market for a cheaper red dot sight and have narrowed it down to either the Vortex SPARC AR or the Primary Arms Advanced Micro Dot. I can get both for about the same price so that isn't a factor. The Vortex seems to have much lower battery life and I haven't heard too many reviews. I've heard mostly good things about the Primary Arms, including positive reviews from guys who have mounted them on high round count shotguns which is a good sign from a durability standpoint. Anything else I haven't considered between these two?