You'll want a fast weapon over a high DPS weapon in that case, then you can provide your spirit regeneration through attacks rather then through runes and can go purely support. If I were you i'd go with a low dps weapon with high stats, life on hit, and +%Attack speed. If you are really lucky you'll find a weapon like mine with a good amount of life on spirit spent (more then the passive) and can just spam your mantra's 3 seconds for self heal and 100% uptime while whaling away at things.
Also considering that even with 4 men in the server if at least two of them have damage (WD,DH,Wiz) you won't be hitting any enrage timers any time soon if you keep the enemies on you (thus they can stack DPS), i'd say go for it.
I managed to find a sweet spot for myself where I can do both at once, but even then I keep a seperate set of gear for group runs that gives me more survivability and less DPS (duel weilding life on spirit spent weapons with life on hit rings and lots of mitigation, I don't worry about Vit, my heals are useless with stacked vit).
*Edit*
Oh and in response to the guys saying you have to carry your own weight in the DPS department. Considering that the highest monk DPS i've seen so far is around 1/4 of the highest WIZ/DH DPS I wouldn't worry about it at all
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