After HAT gets nerfed I will be changing my spec to either mutilate or combat swords. As I understand it, they put out very similar DPS and it's best to go with what weapons you have for the job. Last night in Naxx I was blessed with a great sword and a great dagger.
My swords:
MH - Silent Crusader (156 dps, 2.50 speed)
OH - Hatestrike (143 dps, 1.50 speed)
Daggers:
MH - Twilight Mist (156 dps, 1.80 speed)
OH - Murder (156 dps, 1.50 speed)
So, which spec will help me do more damage? Judging from the weapons, Mutilate seems to be better. I do find Mutilate to be annoying at times because of constantly keeping up HfB, but it's just a minor pet peeve.