Numbers don't always tell the whole story. Some cans are high pitched, others are low. Some are quite loud with FRP (1st round POP). Certain frequencies travel longer distances. Silencer Research & Silencer Talk have some data. You might have to pay $30 at SR for "special access" to that info. Testing cans CAN get pretty eXpensive. ST is brought to you by the same folks that bring you AAC suppressors. Does that mean their data is skewed? Not necessarily, but do your homework. Shooting platforms (make, model, barrel...), ammo, ambient temperature, ablative mediums, elevation, microphone placement... MUST be identical for there to be a valid comparison/contrast. A good set of ears helps, but will never replace empirical testing that can be repeated.
Judging by design & performance parameters, AAC is the outfit to beat in .308 cans. Don't get me wrong, I'm not a loyalist on brand names. I have an AWC MK9 can on my smgs. I have an SWR Spectre on my CZ-75 Kadet & Walther P22. I have an SWR Trident-9 on my Beretta 92FSs & Walther P.5. They are the best cans for their applications even surpassing AAC's offerings (IMHO) for pistols & smgs. *
Joe Gaddini sold the business (SWR) years ago, but his legacy lives on. * :-?
KAC/KMC has become more civilian end-user friendly. Trey Knight is very approachable & responsive. Times are changing. However, military contracts will always get priority treatment. *
Some folks are a little bit ticked at Dr Phil's insisting on getting a ruling from BATFE that resulted in a $200 "GEMTAX" imposed on significant reconstruction of damaged suppressor tubes. * :P
SWR's CS is probably the BEST in the industry! *
The others can be a mixed bag.