IMO hard to get a feel for the abilities / discipline just based off a list and discription. Many of the descriptions are misleading. I'd suggesting changing over to all the disciplines and giving them a shot for a week or so. Just did the quest for switch # 13 yesterday back to harmonious. After you do it a few times its not very time consuming and really lets you compare the advantages / disadvantages of each. Also with all the changes recently, its hard to keep an updated list.

I'll try to help ya out with some major abilities of each class and their function at 50.

Harmonious
-Lower opponents str by 115 for 32 seconds
-Steal 10% of mobs dmg for 20 seconds, adding 10% dmg to you for 1 min (high damage attack) 6jin
-Lower mobs mitigation by 15% for 24(?) seconds
-After a dodge slow target by 15% for 1 minute, you gain 15% haste for 5 mins
-20 seconds of 100% avoidance; 20 min cooldown
-Advanced kick finisher (1 extra rank)

Dragon
-Slightly stronger boundless fist that exploits enraged (vuln granted from boundless fist)
-invs/levitate
-small dot attack
-advanced finisher that increases you next attacks damage by 50% (get adv finisher of a very decent short duration                 dot)

Drunken
-force mob to attack you for 2 attacks (minor dmg)
-aoe taunt forces all mobs within 10m to attack you for 5 attacks (30 sec cooldown)
-advanced finisher for 1k fist chain (2 ranks)
-100% avoidance for 15(?) seconds, 30 min cooldown

Not a complete list, but the ones i use most often for each class. May have forgotten 1 or 2 important ones for some/each of the disciplines. Hard to see the functionality and true power behind some of the abilities unless you test it out first hand. Hope this helps.

It's level 46 dragon style skill.  It costs 8 jin and does not have a recast timer.  The invis TECHNICALLY lasts for 10 minutes (as in, that's how long the buff icon says) but it can wear off at any time randomly, sometimes after 30 seconds or somethings up to 5+ minutes). 

Not much at level 46 that would concern you that wouldn't un-aggroe if you FD.
Surely the answer is to either FD, have a stack of invis potions on you at all times or just collar a friendly invis caster who is probably in your group if your raiding an area with mobs of this level. I can't really see the point of monks having self-invis in the first place because of all the above options being better?