Funny you ask...I was going through the flash hider vs muzzle brake debate last week and decided to go with the muzzle brake and a SureFire Warden (while I wait for the suppressor stamp) to redirect sound if needed. The muzzle brake was not tested (see question below) so it's not clear whether it will perform well or not since the muzzle brake has sort of a mix of the flash hider and warcomp's features.
In the Pew Science review it was deduced that the significant leakage from the suppressor/warcomp interface could be due to the porting (radial holes near the tapered surface) and/or the lack of labyrinth seals. The only sealing interface when using a warcomp is the tapered surface. The flash hider has labyrinth seals but no porting. The muzzle brake has labyrinth seals but also a small amount of porting (
much less than the warcomp). None of these designs are going to seal perfectly at 2-5ksi but the warcomp is missing crucial features that improve the sealing drastically.
It never occurred to me prior to reading the review (it's always obvious in hindsight) but now that it has been brought to light it's quite obvious why the warcomp performs poorly. I'm actually surprised SureFire doesn't recommend avoiding the warcomp. Then again, it's a poor design and shouldn't have ever been manufactured as a suppressor interface. After studying the designs I'm guessing (and I'll let you know in 200-300 days) the muzzle brake will perform close to as well the flash hider with a small penalty due to the porting. The design of the muzzle brake sealing interface is far superior to that of the warcomp.
Sorry for the long winded answer to your simple question. I've been researching this for a few days straight and I felt I should write it all down before I forget why the hell I chose the muzzle brake. PS if you buy any of the 3 SureFire brakes you don't need to buy a PMM or KBA shoulder washer assuming you have the older stepped barrel like I do. It's all included but make sure you read the instructions for direction of the chamfer!