Enhance needs some more sustain in PvP due to the purge nerf, I've also heard they arent the best in PvE.
Nerf stormblast a little maybe 5-10% depending on how big of a sustain buff we get.
Three options to solve this
1) Buff Windfury and frostbands damage also make windfury nature damage.
2) Give us LvB and make it usable with maelstorm (least favorite, but might fix some issues)
3) Make out mastery 30% base instead of 16%
Or give us double purge as a pssive (seems the most approproate)