So yes, we're fantastic single target healers... but in 25-man the other night, with a couple of pallies along to fulfill that role, I found a niche where disc can really provide its own flavor of unique value to contribute to raid survival, in emergency control for raid heals.
If there is a constant barrrage of incoming raid damage (i.e., air phase of Razorscale), spamming PWS works beautifully. Going out every GCD, it absorbs the next 6-8k damage that might be following too closely behind the initial hit that warranted your attention, heals for 1-2.5k, letting that CoH, LB, or other heal that you know is on its way still do its job.
Yes we could spam out a FH, but if the other healers are on their game they're likely to have a heal going anyway, and the combined effect of the shield and that heal seems to yield a greater survival chance.
I started doing this on our 3rd attempt on razorscale (where we downed him), being sure to keep a PoM bouncing, and we only lost one dps in the fight. I didn't throw shields out on those not damaged as it seemed to serve better as a reactive response for that purpose - though there was seldom any time someone wasn't in need of attention. Despite nearly constant spamming of it (switching to single-target heals on the tanks during ground phases) I never even remotely started to hurt for mana.
Has anyone else found themselves doing this, or any thoughts on this?