My first group consists of 1 Protection Paladin and 4 Elemental Shaman, I currently farm several heroics, by farm meaning I do them without wipes (normally ).

I have only 3 healing keys:

Self heal
Chain heal (each one targeting a different too)
Tank heal*4

If I place 4 healing totems (which I usually don't) they'll also tick for around 1.5k.

I used to have a resto shaman but I now find this composition much more effective. I also think that you should only that at a comfortable point of your gear. Having massive dps also means that mobs will hit your tank for less time, bosses will use less special abilities, so it can allow going easier on heals.

On the other hand, my tank is now capped both avoidance and defense and my shaman crit at 6k+ lhw, so it makes things easier oc.