Excellent optic, it's a cheaper t2 with extra steps - Holosun Military Grade Micro 1x22mm Red Dot Sight

I got this a while back and have been very pleased with it. I have astigmatism that isn't corrected, so I'm pretty leery of red dots. My Aimpoint CompM4 looks okay in highly lit environments but my friend's Sig Romeo5 completely blooms out unless on very low settings. The HS515 I was sent has a very clean reticle with no smearing/smudging (that can be a factor on many Holosuns, like the HS510 and HS512). For whatever reason, the circle dot reticle does not bloom out on me until you get it to it's near-maximum brightness. I read somewhere that the circle dot helps trick your eyes, but your mileage may vary.
I was initially going to replace the mount, but then found that it was so sturdy and well-made that there wasn't a need to do so. Thus far, I've been downright savage with the thing on a few competitions and countless drills and it's not lost zero, nor have I had any malfunctions. The brightness settings are a little finicky at times, and if you're in just the right amount of light at dawn or dusk, you run the risk of it being either too dim or too bright. Another thing that was more annoying than anything was the rear lens cap would not come off for the life of me. Tried just about everything with it, but I didn't want to end up damaging the dot. So there it stays. It doesn't impact anything particularly badly, it's just irritating.

Overall, I am extremely pleased with this optic. I've heard that this is about as close to an Aimpoint T2 as possible at a fraction of the price and I would say that's accurate. Some caution to folks if they want to upgrade to the titanium/high grade aluminum housing "HE" unit: what you get with the HS515GM is so good for the price that I think you encounter the law of diminishing returns by spending more on the HE515. We're talking about an extra $100+ here. If you are going to do that, I would just go ahead and upgrade to an Aimpoint T2 and bypass the HE entirely.
I haven't managed to test the NV settings just yet but will update my review accordingly.