I have the Omega 300 with brake, but so far have only been using it on .223/5.56, 6mm CM, and .300 BO firearms. I just purchased a Bravo end cap so I could remove my brake, because it is supposed to give me a few extra dB reduction. I really don't think the brake on the end does much from what I'm shooting.
I can tell you there is no noticeable difference in recoil or muzzle rise between the Creedmoor shooting 105 Hornady Black with the brake or the cap. I still put plugs of muffs on to shoot the CM and other supersonic rounds so I can't tell you the difference in dB rate. Subsonic .300 BO sounds like a springer air rifle until those heavy bullets strike steel down range.