From what I've seen, Monk is the big loser and might require some big adjustments in 2.1. A Monk can certainly keep up in a straight up tank+spank scenario. The issue is that Monk DPS is very fragile and cumbersome.

1. Fragile because it is the most dependent on positioning and the buff timers for GL+TS are super tight. Encounter design has potential to be super punishing to Monks. Losing 3 stacks of GL because you had to run out of a PBAoE will do nasty thing to your output. Its also the only class that is 100% useless outside of melee range.

2. Cumbersome because of AoE mechanics. A Monk's spammable AE attack is both the weakest and expensive. Its hard hitting AE attack requires 2 GCDs (one has to be a single target attack) and its only a conal. Comparatively, DRG has a spammable AE that does twice as much damage and combos nicely with Heavy Thrust (increases the difference to 3x).

That said, Monk is probably worth bringing just for the super buffed Mantra.