The quote below is from a Chuck Hawks article on dangerous game rifles. Brian Brown.
http://www.chuckhawks.com/bolt_rifle...erous_game.htm
Muzzle Brakes
Muzzle brakes should be avoided on any rifle used for hunting dangerous game. As nice as is their recoil reduction capability, the (literally) deafening report of a powerful rifle equipped with a muzzle brake leaves the hunter unable to hear for some time. This creates a bad situation, as sometimes it is necessary to hear a dangerous animal coming to avoid being eaten or stepped-on. This is especially true when hunting animals that travel in herds, prides, or packs. Hunter injuries and deaths are often attributed not to the target animal, but to another that attacked from behind. In such situations the hunter's hearing is his only early warning system.
A secondary consideration is that muzzle brakes are illegal in some African jurisdictions due to the damage they cause to the hearing of scouts and gun bearers. And, for much the same reason, many North American big game guides will not allow clients to use a rifle equipped with a muzzle brake.