I just see your issue on SimC and you have made a mistake. You used the Frostfire's profile instead of the Frost one.
For the glyph case with T12, it's a difficult choice:
- MA's glyph is better on single target fight with +2% crit for all spell but -3% for FB.
- FB's glyph is good on a boss +2 add type fight because of Piercing Chill.
4.3 will be released in a few weeks now (PTR built marked as releases), we have to see how the 4pcT13 work and what will be it's influence (glyph, rotation, etc). On the last built, Iv have it's cooldown reduced by 15s for each stack of Stolen Time. It's means that it's CD will be reduce to 0 when we obtain the 10th stacks. The game play will change to 2 phases: stacking buff (for 17s to 34s) and a burst phase. With this much haste, we will burn a lot of mana so we will have to see if we can continue with Molten Armor + Evocation or if we will have to switch from Molten Armor to Mage Armor..
edit> For those who think that IV will bring us under GCD, we will have to reforge Haste to cap it at 25% raid buffed (50%/20% = 25%). So we will have to obtain 16.71% (2139.83) haste from gear so I don't see a problem here.