I run a mostly melee group {see sig} .

prot pally would tank, provide imp devotion aura, blessing of sanctuary, and also toss holy lights that splash to entire party
Your tank will NOT be healing. Any non-instant cast spell brings your block and parry to ZERO. You will have no mana pool for casting Holy Lights anyway. You will end up taking far more damage than you heal, and even if you could manage to land heals, your mana would be way better spent continuing your tanking rotation.

Blessing of Sanc will have next to no use on anyone other than your tank. If your other toons are dodging, blocking or parrying enough to see any return whatsoever on BoSanc, then your tank is not doing his job. Your major Glyphs should be Hammer of Righteousness, Divine Plea and Seal of Vengeance.

I read earlier on here that to do adequate dps with an enhancement shaman takes ones full attention, as opposed to the very simple ret rotation.
Enh shaman take no more attention than rets do, it's still a single proc to worry about, everything else can be shoved into a single click sequence.