Which two pieces should I be wearing?

[Barracks00]

Here's my armory: http://us.battle.net/wow/en/characte...ation/advanced

I can either wear Living Wood Raiment + Living Wood Headpiece to take advantage of 2 piece bonus, or I can wear Rune-Enscribed Hood + Chestguard of the Roaring Crowd.

Which combination should I go with? The set pieces are only 665, where as the other helmet is 685 and the chest is 670. I hate dropping 20 ilvl on one piece, but 12% faster cast speed on my two main spells is pretty big. My main spec is balance, but I also heal. I don't feel the 2 piece bonus for healing is quite as powerful so I usually go with the non-set pieces.

[Varna]

There is this thing called SimCraft, it's pretty handy you should look it up.