Rule 1: Type out "priority." Your abbreviation is unnecessary.
Rule 4. I'm not saying your wrong. But your tone could have been better.
I've been considering a bit where Resto Shamans might go from here, and quite frankly, post-patch I see no future in 10mans, not that there was much to begin with. However, what really bothers me is that with the mastery and GHW change, there might have been a real opportunity to use Shamans stacking int>mastery>haste and casting TW-hasted GHW's, trying to act as a life-saver whenever someone dropped low. This would have, finally allowed us to get some real mileage out of our mastery without eating into the benefits, as we currently do with HS/CH/HR (i.e. each consecutive heal gains a smaller benefit from mastery, where as GHW heals in a larger lump sum which is all effected by the higher amount of mastery gains existent when the heal was cast).
The problem, naturally, is that after swapping around gear in order to play mana battery, we're down by ~1k Int for the reasonably well geared Shamans currently. And the spell that takes the biggest hit from this is GHW, which assuming the coeff now goes up to 0,9, would lose about 1/4th of the buff to it due to how we are forced to change our gearing. Worse yet, having tested this on magmaw HC yesterday with HS spam (without mastery stacking, as it doesn't make sense for HS), this kind of role is a heavy drain on mana, and the loss of double-tide regen further hurts this kind of strategy.
Ironically, what seems will be hurt the least is the current haste>crit>mastery secondary stat prio and a raidhealing CH/HR/ELW spam mindset. So the net effect of the change? Worse regen, a bit less HPS, and less room for diversification of tasks in a raid environment.