Grp consisted of prot war, combat rogue, assasination rogue, and ret paladin. Since recount is not up and running for me yet, no hard numbers, but here's what I noticed:
Between replenishment and symbol of hope, never dipped below 50% mana at any point in the run.
Tank went from 0 rage to 100 in about 2 seconds even with a PW:S up.
Penance is even more efficient and uber then I'd hoped it would be, just shy of 50% of the mana cost of max rank Gheal and hits for about 1600 a tick with about 1030 SP, can only imagine how this will scale come the xpac.
I intend to test this in a raid, probably BT, in a couple days when mods are fine-tuned and running, hopefully be able to provide a full in-depth look, but initial impressions, discipline is most definitively viable for PvE healing. Hopefully I'll be able to provide a side-by-side comparison against other healing classes.
Edit: Here's my spec: http://talent.mmo-champion.com/?prie...00000000000000
Also, I'm going to do some experimenting with swapping out some of my +spellpower gems with a crit gem or two, currently running with 13.5% crit chance and saw a fairly decent crit rate, but going to see how much higher I can take that without sacrificing too much spellpower.