Would it be more viablo to stay 4 ele shamans, or 3ele 1 resto?

I could have the resto one heal for every lightning bolt, because I have a pally im running instances with.

or should I just DPS like mad and switch off to heal as needed?

I'm only level 16 so i'm talking in the future.

If you had performed a successful search, you would have found that most suggest using all 4 as elemental until high 60s

What I did was collect healing gear on one of the shamans so I could respec if I needed a healer. For leveling you won't need to do this you can just zap everything but it's great for end game.