While I haven't had the Surefire long enough to give you an exhaustive review, I will say this.
They have a locking and indexing system on the SOCOM suppressors that is unlike anything else I've seen.
I'm not saying there aren't other options out there that do the same thing, just that I've never seen a can do
this.
The SOCOM has a locking ring that rotates independent of the suppressor body. The ratchet teeth are contained inside the locking ring and are protected against wear and damage. When the ring is fastened to the flashhider (or muzzle brake), there is a notch on the bottom/inside of the suppressor body that indexes it with the muzzle device. This results in the baffles being oriented in the exact same location relative to the bore, resulting in a miniscule and extremely predictable POA/POI shift.
I've shot AAC's SCAR-H, 762SD, and SDN-6, as well as Surefire's SOCOM RC. The AAC silencers seem a bit over built to me, but I think they are benefiting from that in terms of increased sound reduction. Regardless, both brands will result in a hearing-safe rifle.
Now this is extremely subjective, but here is how I would rank them in terms of sound reduction:
1. SCAR-H (on 16" OBR)
2. 762SD (on 16" OBR)
3. SOCOM RC (on 18" OBR)
4. SDN-6 (on 16" OBR)
5. SOCOM Mini (on 18" OBR)
Again, that's just going off my ears--no science involved.
Also, it's worth noting that the actual sound of the blast will vary with suppressor models; some cans sound like a crack while others like a thump.
All the AAC/OBR combinations I've fired do not belong to me, so I don't know how reliable they are after thousands of rounds/different combinations of ammo. I do know that the SCAR-H would run no problems. I think the SDN-6 hand to have the buffer weight/spring messed with to get it cycling right.
Either way, if you go with the Surefire, you won't have problems with the OBR/PredatOBR
At my aforementioned range trip, I put Winchester 147gr M80 ball, Federal 168gr GMM, and Black Hills 168gr through my SOCOM Mini equipped 18" OBR with absolutely no problems.