well, i just respecced my priest Disc, and wow what a difference.
I had to change a couple macros to take into account the lack of CoH and the new PI and Penance, and only rand H VH since. But i didn't have to drink once. not once! basically the 5-10% missing are filled up by the time the next pull arrives.

As holy i had to fill up the 20-30% missing mana every pull or so.

My renews are considerably smaller (1350hp instead of 1800 i think) but the shield are nice, and penance is king of heals.

Thanks for feedback guys.