Seeing as theres less that 10% difference in DPS between Harmony and Dragon, id pick Harmony any Day.
We can solo things a dragon monk cant solo, and have Massive debuffs, which i am sure will be Very useful on forthcoming Raids.
Debuffs as follows: -
Withering Palm -10% damage to Mob for 20 Secs +10% Damage to Monk for 60 Secs
Quivering Palm -50% damage for 8 seconds
Eagle Claw -15% mitigation for 24 Secs
North Wind Snaps the Limb II -150 damage for 30 seconds
North Wind Breaks the Trunk II 300 Damage every time mob attacks
Steal the Wind III -15% attack speed
Trappin Mantis claw III 2 second stun
Pusing hands Takes Mob out of stance (apparently being implemented in Raid)
Also if you have one of these
http://vg.curse.com/database/items/details/586680/ will slow attack speed and cast rate by 15%
And lastly book of Morfair + 10% damage to whole group (assuming Necro can Undead Mob if not undead already.
So Harmony Monks Tanking Big Mobs isnt out of the question.
Pull using: -
Diamond Skin II
Reed in the Wind
Swaying step
Iron Skin
and Find the center
Pretty much nothing will touch you for 20 seconds, in this time Mob is attack is slowed for 30% Damage reduced by 50% plus -10% plus -150 Damage, also by which time you group would have also let off some decent debuffs rendering the attacking mob more a less pretty useless!
I used this strat tanking Heg during the fight he hit me maybe 4 times but my HP barely moved west during the whole fight.
Be interesting to see what happens during raids but having a harmony Monk pull, open an attack debuff wouldnt be out of the question.