Our progress is now 15/16 HC 10 man. I'm a resto shaman and my healing partner has been a resto druid throughout the progress. The difference between resto shaman and a druid is quite small. Shaman has better cooldowns (healing tide > tranquillity, ascendance > tree of life+ nature's vigil), druids overall mana efficiency is higher (atleast when paired with shaman due to mana tide). When you are "normally" healing your tanks/raid, druid is slightly more efficient mana and hps wise. Shaman is more bursty and shaman needs to setup a majority of his heals. Druid is very mobile and stable. But when it comes to cooldowns, shaman beats druid hands down.