I've already thought it through myself awhile back. You'll still need to be doing alot of melee damage even with shockadins. It could be fun but wouldn't be really viable till you get to outlands and actually really start being able to get some good gear for it me thinks. I dropped the idea though when Blizzard reitemized ret paladins. I was thinking of going with 2 handed shockadins stacking Strength/ Spell Damage but they changed all the Ret gear to phase out spell damage so know you'd have to go after more enhancement shaman gear, at least when you got to epics anyways. That's my 2c.