I have a BAR in 300 mag with a BOSS. Started out with the brake version, but after shooting one deer with it and having noticeably more intense ringing, I switched to the CR version (Conventional Recoil). Given how much recoil the action of the gun absorbs, I don't see that you would need the recoil reduction that the brake would give; my 300 is quite manageable.
As far as the accuracy, the BOSS certainly works. As mentioned above, it does allow you to dial in a specific load for your gun. I am guessing that you aren't looking to enter bullseye matches with the gun, probably more along the lines of a "minute of a deer", so maybe you aren't concerned about tweaking to get that last bit out of a specific round. A lot of people will shoot a few different factory loads and go with what groups best.
Besides the accuracy and noise, let me say that the extra barrel length does make them a little more unwieldy in the woods. For the mag calibers, it nets 3 additional inches of barrel length; I can't remember if it was the same for the standard calibers, or if they were a +5".