Rambling pre-coffee comments/thoughts:
I personally like the AAC 762-SD better than the SCAR-H SD for a fast-attach 7.62 can.
The SCAR-H is a bit quieter but not by much to my ear. The Cyclone is just a bit quieter than the 762-SD.
Thread-mount cans are okay if dedicating it to one host. I use my 762-SD also on an FAL and a few other host weapons. Mounts are available for just about anything from HK guns (15mm) to FAL, L1A1, M1A, etc. You could even use it with a .5x28 mount (same as for M4-1000) on your AR.
The mount on the SCAR-H leaks gas. This is true of most (if not all) fast-attach cans. You will usually get a little gas blowing back from the back of the mount. Ops Inc cans have a friction fit on the rear collar so they don't do this. Thread-mount cans don't either. The gas escaping the SCAR-H mount is greater than the gas escaping the 762-SD mount. The SCAR-H can does not have a full rotation to lock the can onto the mount.
The MITER mount is neat to some users. My biggest concern is that a can always indexes back to the same place. My 762-SD does that just fine.
I was testing out the new Nightforce first focal plane scope yesterday on my Rem 700 PSS with barrel cut to 20":
Accuracy is great. I get very little POI shift (less than 1 MOA) on this rifle.
The SCAR-H SD is a great can. I just like the 762-SD better for my uses.
A local PD wanted some .30-cal cans last summer. We tried a few different solutions and came up with the 762-SDs as the best fit for them. I wrote up a few thoughts on the little project
here.
Okay, off to find some coffee...
Take care,
Mark