Rain of Fire is channeled for Affliction, Hurricane is channeled for Druids. However only RoF got treatment of "you spend mana only for ticks you cast". Blizzard and Hurricane are still "you pay full cost up front".
Also let me remind yuo the Fire is still only spec that has no AoE while leveling: Flamestrike becomes spammable only when you get perk, other option is level 75 talents. I wonder what will happen in a month (or weeks) before WoD with competitive raiding in SoO for Fire.