I would recommend you run a log parser, with sustained buffs, a consistant target, and find out for yourself. In short-burst MM does better, but has a faster fall-off. Sustained fights all 3 are fairly close and within 25 DPS of each other which can be accounted for by user error and missing "heartbeats".
None of the specs are bad, it all depends on your playstyle, PvE vs PvP, and the goal you need to achieve.