The Omega 300 Anchor Brake works really well. I have an A-Bolt 3 in 300WM (7lb naked, 10 lb w/ bipod, scope, etc) that kicks hard without any muzzle device. With a brake, it is more tame but my face still feels the concussion.
The Omega 300 turns that recoil into a longer slower push, no concussive blast/force, and reduced recoil. Another person a few stalls down at the range had an Omega 300 as well and his muzzle report was like someone slapping a heavy phone book on the table. It was far far nicer to shoot. I couldn't believe it was the same 300WM rifle.
My Omega 36M doesn't have the anchor brake, and the rifle still kicks pretty hard although not as fast.
The Omega 36M and Omega 300 are similar in size/shape and number of baffles (Omega 36M has 1 additional baffle and is slightly longer).
I am not sure about longer cans (TBAC Magnus) or cans with more baffles (e.g. OCL Hydrogen S), although I am tending to think those won't cut down much recoil versus the Omega 36M.
I suspect the people that feel the Anchor Brake is a gimmick are shooting lightweight calibers. I have heard the Anchor Brake works more and more effectively with bigger magnum cartridges.