I'm going to go against the prevailing opinion a little here. Shot side by side with a Gemtech, I personally could tell no difference at the shooters ear when mounted on a 30-06. Perfectly acceptable unless you were simply going for maximum sound suppression for the sake of suppression. On a mid caliber hunting rifle, it's great IMO. On a big magnum, I suspect the small size and limited baffles might make more difference.
On a .338 WM, it's a bit louder, but it's also the ONLY can I found in that weight class for a .338. The .338 is specifically a thick terrain rifle, so a longer heavier can is not going to work for my application. With the barrel cut back to 18", it's ideal and maintains factory balance and weight. The goal here is to simply eliminate hearing damage for a few field shots a year. It will take care of that nicely. Again, I expect with a .338 Lapua class magnum, it's probably not the right choice.
I considered the AB Raptor, but it wasn't in stock in .338 at the time of purchase, and is also not rated for the barrel length I wanted. AB recommended considering going to a larger .375 Raptor 10 can if I wanted to cut the barrel back, but that wasn't available locally either.