I get the feeling that HYBRIDs are screwed with the mastery.
if you actually put all talent points in one tree its (maybe) OK, but if want to take up talents in other trees, you get no real benefit.
say, in Elemental tree you get spell damage, but if you put points in Enhance, you will get Melee damage and Melee haste??? I don't know if Elemental shaman will melee also in cata...
see mage or warlock for example, either way you will get Spell damage...