For me any healer is easy. Be it paladin, monk, druid, priest or my beloved shaman - they are all braindead simple. Strangely, I thought that any member of a top ranked guild can play any class at exceptional levels with closed eyes.
Shamans are great for first day phase in heroic tsulong.
Monks are best overall.
Since it's relevant to the conversation about Resto Shaman performance in HC Tsulong: Why HM Tsulong should make you look at Ancestral Guidance again (I actually just posted it last night).
And although I concede Hamerfal's point about why Monks' sustained throughput trumps other classes' performance, it is notable what a Resto Shaman can do with Light of Day and Ancestral Guidance. So, the consideration at that point is really can shamans' burst outweigh impact that the loss of one of The Light of Day buffs, per Day phase, would have on the Monks' HPS.
@ OP - If you were blowing them out of the water before, Nym, then I'd be delighted to see what you can do with AG.
Here is a log of our 2% Tsulong wipe tonight. We had 2 resto shaman taking the first set of Light of Days on each day phase 6 seconds before Sun Breath and popping every CD (Ancestral Guidance/Elemental Mastery/Ascendance/Intellect pot). You can put all of those abilities in a macro, and also add Spiritwalker's Grace to the same macro so that you can run from the Light of Day spot in front of the boss to get the breath buff with all CDs up just as the Light of Day buff wears off. After the first set of Light of Days, other healers grabbed them.
Shaman do significantly more throughput than any other healer with full cooldowns up like that, so it is well worth setting it up that way. The risk is that not taking Healing Tide Totem, Primal Elementalist, Ancestral Swiftness, etc reduces our raid healing cooldowns and throughput, so it may be difficult to get through the night phases.
I *might* be able to test a Shaman on this fight at some point when we meet HC Tsulong in our alt raid (we only have 1 Mistweaver in the alt raid). It would be fun to see, but I can't see any class beating a relatively knowledgable Mistweaver, they can abuse so much with Soothing Mists it's ridiculous.
Well.. There´s resto shamans and resto shamans. Personally i love healing because there is no rotation. Of course some spells gains huge bonus if you cast those first. Healing depends on situation. You can play healing meters or kill heroic boss.