OK, I'm going to be an outlier here, but when I list the factors that are most important to me in a suppressor, how well it actually suppresses sound is probably 3-4 on the list. If you're shooting 5.56 your going to be using some kind of hearing protection anyway and frankly I'm not sure I'm even going to notice 3-4db's in sound reduction. I would also add that tone makes a difference as well.
So what is important? Well I want a decent attachment system. Yes, I know OP said this was just going to be used on a single gun. But if he has or gets a 2nd, 3rd or 4th AR he's going to want to be able to switch between guns. Once you start shooting suppressed it's hard to go back.
I also care about durability because I want to have the freedom to attach to a 10.5" SBR and do mag dumps without worrying that I'll damage the can.
I shoot left handed so low back pressure is a big plus, although my current cans do not have low back pressure and I can live with them. (I do have a couple of guns with adjustable gas blocks and a piston gun which helps). But even for right handed shooters a low back pressure can will be more pleasant to shoot, is probably better for your health if you shoot a lot and won't require you to mess with adjustable gas blocks, buffer weights, etc. So I think low-flow cans are the future of suppressors.
Size and weight matter, unless you're just going to shoot off a bench 100% of the time. If you shoot a lot offhand you're going to notice an extra 2" and a couple of additional ounces hanging off the end of your barrel.
Finally, I suppose there's something to be said for brand loyalty, particularly if you find an attachment system you like. My first can was a Dead Air Sandman S, which I switched between 7-8 different rifles, followed by a Sandman Ti, which I've used in 3 different bolt guns. I even own a Sierra 5, which probably has 4-5000 rounds through it. I sometimes feel like I'm the one guy who hasn't had a problem with this can.
Just recently bought a Lazarus 6, which I haven't gotten yet. But I've been pretty impressed with the reviews, I like DA, and I already have the mounts for this suppressor, so that will be a savings. And I know you have a $1500 budget, but Botach is having a sale on these $630 if you use their july4 coupon code. Just something to think about, although there are a lot of great options out there.
