Just an idea; how would it work, if only during Colossus smash your base GCD would be lowered to 1s? Or even if it would be baked into some mini cooldown like hitting that Berserker Rage. At least for Arms it's kinda irritating that "you're supposed to hit slams" during CS but never have enough globals to do so unless you want the OP stacks to go up to 5.
Maybe that would complicate things too much, but on some situations I would be so much in for smaller global cooldowns even if it would be temporal, since it makes warrior just more clumsy than the others in some situations.