I love the BOSS, got to borrow a buddy's model 70 30-06 w/the boss brake for a weekend once. Recoil was very light. You use the provided chart to dial in the BOSS setting to match the ammo you are using, and bingo! she shoots nice and tight.
The only downsides to the BOSS brake are
1. the brake model was very LOUD. I wouldn't want to shoot one without really good hearing protection.
2. I handload anyhow, so the BOSS isn't really necessary to for me to tune a load to a rifle.