My dad has the BOSS system on his 7mmRM A-bolt, and it works well, as far as we can tell (I mean, it's pretty darn accurate to begin with).
Most BOSS rifles come with two BOSS systems, don't they? One with a muzzle break and the other that's "normal."
My dad switched from the muzzle break version to the non-recoil reducing one, and is much happier. Ten years ago on a muley/whitetail hunt in Nebraska, it was splitting his ears in wide open country! Have you ever tried switching the BOSSes out?