The cross holes and cavities re-direct the gases to reduce recoil. The variances in designs may have some effect on it's ability to reduce recoil, but basically they're all the same concept. The "brake" (notice spelling) should have an exit hole for the bullet that is .017 to .022 over bullet dia to be the most effective, but when exit hole is that tight, it's concentricity with the bore becomes critical. Most aftermarket, customer installed brakes have a larger exit hole to eliminate the concern for concentricity.
If you are looking for a brake for an SKS, here is a guy that is selling some quality brakes. "Ricks Muzzle Brakes" http://www.ricksmuzzlebrakesandgunstuff.com