Chanrek,

You are still missing one important point.  Hunters don't like melee.  While the DPS is better with the dual wield, losing the agility really hurts a hunter when they are using the bow.  Being a hunter, I get out of melee as soon as possible.  With the cost being so high, dual blading these would not be worth it at all.  On top of that, the agility would make a hunter (and his pet for BM) much stronger with Terrokks Quill.