keep in mind, affinitii from vodka also played a disc priest instead of his normal (these days) monk in their kill of gara'jal at least.
that being said, the play of the extreme upper end of progression shouldn't signify the necessity or lack thereof of buffs or nerfs, those players are just out of this world. gotta look at at least the first... 1000 guilds together. :p
Yup, and keep in mind Gara'jal is one of the fights where a disc priest when put on a tank, causes a 'gimmick' effect and makes them go off the charts in terms of effectiveness and damage prevention.
As for paragon 10s. Something like the below may work:
In a 10 anyway. A disc priest, if backed up by amazing raw output healers (of which paragon undoubtedly has), is basically a huge powerhouse of CDs. If the disc priest doesn't have to concern himself with healing normal raid damage. This is what happens.
Spirit Shell + Archangel CD + Inner Focus'ed (your choice of spell here) every 1 minute
Spirit Shell + Archangel + Power Infusion + Inner Focus'ed (your choice of spell here) every 2 minutes
So every 1 minute the raid gets a major raid CD that can be combined with OTHER raid CDs. With a good tank CD, a good raid CD (fight depending) and absorbs, that's a ton of utility and raid saves. The only issue here is mana, mana mana mana. But if you have powerhouse-level healers backing you up, you can most probably regen safetly for that every one-minute burst.
And keep in mind this is a ten. Damage is lower, combined with POH spamming on only two groups (instead of 5 which spreads it out a lot more). Spirit Shell + Archangel is probably doing something amazing in terms of damage saved. And you don't have to use it every 1 minutes...it is available every one minute. So if you line it up with boss phases...I can see where a disc can be powerful in a 10.
This is, of course, me grasping at straws.