Kortar, you forgot one big thing. Ancestral Awakening is going to add a 60% heal to another target whenever we crit, massively amplifying the effect of those 14% bonus crit that we have available.
I didn't so much 'forget' it as 'omit' it as it isn't terribly relevant to tank healing in a raid setting. If the Resto Shaman is solo-healing a 5-man instance, this ability will be incredibly useful. But in a raid setting, you're more concerned with reliable burst healing against the one target of interest - the tank - since other healers can cover the non-tank damage.
Do ancestral awake heal 60% of total healing done by crit or only effectively part?
There's a model for this type of talent: Ignite
So I'd argue that Ancestral Awakening would provide 60% of the critical - for 90% of the normal heal.
In any case, let's presume you have 25% critical (talents + gear) and +3000 healing.
On the primary target you'd have (3260 + 3321) * 1.18 * 1.1 * (1 + 0.25 * 0.5) = 9610. On secondary targets you almost certainly wouldn't have Healing Way, so it would be (3260 + 3321) * 1.1 * (0.9 * .25) = 1629. Note: These figures are short-handed a bit since I'm just using them to show hpm/hps.
The total heal is 11239. With 1520 mana, that's 7.39 hpm and 4496 hps (note that this is substantially lower hpm for about 150% the throughput of current Chain Heal).
With current talents only (and no Holy Concentration), a Priest with 10% critical and the same +3000 healing would heal for a total of 8594 assuming none of their situational talents were active. With 1097 cost, that's 7.83 hpm and 3438 hps. IHC would increase the hpm to 9.08. Presuming an 5:1 mix of Greater Heal to Flash/Binding Heal to maintain IHC, the Priest would have 88% uptime on 60% haste, or a total of 5246 hps. And that's before we even starting considering any of the other high end Holy talents for Priests.
I'm not really going to set up a completely spreadsheet detailing all the possible spells and downranking, but it should be apparent that if you need controllable burst on the tank in a raid setting, Resto Shaman aren't really even competitive. Nor can you really 'throw away' the initial hit of the Healing Wave like you can with Chain Heal, since it's so much of the healing. So you need to find someone who can take a heal that big - which is unlikely if you're not healing tanks.
My suspicion is that means that Lesser Healing Wave will get more out of this in a 25-man raid. So let's look at Lesser Healing Wave. We'll still have +3000 healing and +25% critical. We'll ignore the fact that it's almost certain that the empowerment talent will be changed to reflect different levels on LHW/HW. So we get a heal for 4647 on the primary target and 25% of the time we'll get a 3718 on a secondary (5576 total). With a cost of 917, that's 6.08 hpm and 3717 hps against one target every 1.2s. Currently Chain Heal is more than double this efficiency, heals one target every 0.83 seconds, and has about 60% of the throughput noted. Additional ranks of Chain Heal will probably close the hps gap quite a bit.
Even in terms of the armor buffs, our Priest is going to being casting about once every 0.8s compared to our Shaman's every 2.5s. Which means that even with discrepancy in critical, Priests will still have greater up-time on the armor buff.
Comparisons against Flourish are essentially impossible since we don't know how the coefficient will work, or what the healing curve will be on Flourish, but it's almost certain that Flourish is enormously more efficient than anything a Shaman could possibly come up with - a reasonable guess is that Flourish can potentially do around 25k of healing for under 400 mana. More importantly, it imposes a significant boundary on the utility of Shaman multi-target heals - the only niche they might occupy is in providing bursts of healing beyond what Flourish can accomplish. But even here, you're still talking about taking some major hpm/hps hits over what Holy Priests could be doing with their single target heals.
Basically, what I trying to get at is that the various Resto Shaman talents seem to work well for solo-healing in 5-man instances - Spirit Link compensates nicely for the relatively weak single target heals - but in a raid setting, Healing Wave/Lesser Healing Wave and perhaps even Chain Heal will be so much worse than what other healers bring to the table that you'd have trouble justifying a Resto Shaman as a healer in your raid.