How important is Frost Armor in PVP?
I understand it can be an invaluable skill against physical DPS classes, because it can proc numerous amounts of Fingers of Frost, but I noticed that my mana runs out very quickly without Mage Armor's mana regen. Being a frost mage, just the sheer amount of frostbolt and ice lance spamming drains all of my mana after just a 5 minute skirmish. I personally default Mage Armor in PVP battlegrounds, for the -50% duration on a variety of CC, but largely because of the mana regen.
Is Frost Armor used often in arena and battlegrounds? If so, how do you personally manage your mana when using Frost Armor and not mage armor?
Opinions are appreciated.