Wow, I rarely see a Mage post here at TankSpot. Well, I generally lurk here to get info for my alt warrior, but my main is a Mage, so here goes.
It sucks to have spent hard earned badges on an item (especially if you dont get many chances to get more badges), only to get it replaced a couple of weeks later, but since you don't have any of the Tier set bonuses to worry about, your new chest piece is definitely better. Haste pretty much always beats crit for an arcane mage.
I was going to tell you not to switch to the FFb spec, but it doesn't look like you're raiding, so for heroics any of the cookie-cutter specs will work. Although Arcane is probably still your best best bet.
A couple of other things I noticed:
1. Change your Meta Gem in your helm when you can. The Chaotic Skyflare Diamond is the only good mage meta for non-PvP activities.
2. Whether you use rare or epic gems, you should always get the following:
Red: Runed Cardinal Ruby or Runed Scarlet Ruby
Yellow: Reckless Amertine or Reckless Monarch Topaz
Blue: Purified Dreadstone or Purified Twilight Opal
3. Run regular ToC 5-man until you get the Abyssal Rune Trinket. Also, use any Triumph Badges you can muster to buy the Talisman of Resurgence Trinket.
4. Replace Glyph of Arcane Barrage with Glyph of Molten Armor, and then always use Molten Armor. Aracne Barrage is only worth using when moving, since they nerfed it a couple of patches ago.
Hope this helps.