I'd avoid the warlock AND balance druid together. The the warlocks curse of elements will override the druid's Earth and Moon, losing a big effect from it. For dpsers, the arcane mage, elemental shaman, and balance druid would stack together well, and the balance druid's debuff comes automatically with the first wrath or starfire hit - no special, extra spell cast that wastes time otherwise while dpsing.

Personally, even if my balance druid caught up in DPS, I'm not sure I'd replace my hunter with the druid though. The usefullness of misdirect and pet stun are used SO often in my heroic hunts, that losing them would be huge for me (not to mention the hunter does massive damage output).

Seems like you are missing a healer? Could use either a resto shaman, priest, or resto druid well. While I like the spamming ability of a holy paladin, I don't like losing group healing (though don't they have a Glyph that does that now?).