See and I think the reason I was OOMing like mad in gold is I'm dispel happy (I'm not kidding on this). I see a purple debuff, it gets dispelled.
So on my final try I went with the TC and HW glyphs. Seemed to help a bit.
I honestly didn't find much of a problem in gold. I dispelled everything (it's more mana efficient to dispel than to allow the bombs to explode, after all), I was careful not to overdo my healing.
I think shammies have an easier time than other healers though, purely because we have so many cooldowns. The new rushing streams talent is excellent for non-critical 'aoe' healing, and with totemic recall, healing stream totem is basically free. We have capacitor for stuns (and if you time it correctly, you can make THAT free as well using the recall, but it's only 3k mana either way). Healing tide makes for fine emergency AoE healing. Ascendance is very powerful in a 5 man group as the healing doesn't get watered down nearly as much. And we have a ranged interrupt.
My breakdown for the endless waves, if it's of any use to anyone:
Versus the mantids/ordos: Focus interrupt them, but not right away as the rogue and mage generally get the first couple. Against the clumps of 4 ordos casters, wind shear the far one to bring him into melee range of the tank, then drop a capacitor totem down after the tank's hit his shockwave. Trigger finger to be kept near healing tide totem as these can be high group damage.
Versus the virmen: Allow the tank to take some hits where you can, in order to dedicate full attention to getting the debuff off of other party members. Given how resto's mastery works, this actually works quite nicely as long as you don't neglect him too long. Trigger finger near spirit link totem so you can pop the tank back up to an acceptable level of health if it's during a conqueror pack.
Versus the jinyu: Auto dispel the debuff on reflex if there's only one. if there's two, wait and see who's targeted. The debuffs go out within a second of each other usually. Dispel in melee. Leave yourself or the hunter with the debuff. Run out of melee if you have it. One explosion won't be fatal as long as everyone's healthy. They actually do melee kind of hard, too. Probably the most dangerous enemies in the healer challenges, I think.
Versus the conquerors: Unless you've let the tank dip low enough that he shield walls out of sequence, he'll always pop shield wall during enrages. Which means unless there's two conquerors in the group, he'll be fine and you don't need to do anything special. Trigger finger on ascendance if there's two. Spirit link as well, if you messed up and the tank can't shield wall.
And lastly, mana tide whenever mana falls under 220k and it's off cooldown, unless you anticipate having a good 10-20 seconds of no casting at the end of a wave (waves 11 and 21 felt quite easy and short, so these made fair mana recovery stops). Try to time after healing stream expires so you don't waste throughput.