Here's what I found on EJ, even after reading it I am confused about how much I need to go for. I don't even know if Dual Wield Specialization applies to anything other than melee attacks (though I hope it does).
Quote:
Changes to the unified hit rating mechanic and an increased use of spell damage abilities due to Maelstrom Weapon have greatly increased the need for Hit Rating for Enhancement Shaman. While there is still no need to reach the DW hit cap for melee attacks, the spell hit cap has become very important. Recommendation is to gem/enchant to hit the Spell Hit cap, keeping in mind that you can get 3% spell hit from raid buffs (Shadow Priest - Misery), and you can also consume a Hit Rating food buff. Draenei of course have another 1% hit that they do not need to gear for due to their aura.
Spells have a miss rate of 17% (16% for Draenei) against level 83 (Boss) targets, but this is lowered to 14% (13%) after raid buffs. Spell hit correspond to hit ratings as follows::
17% - 446
16% - 420
14% - 368
13% - 341
Halp?