So as Moz and me and Aeth have had a discussion over in the WoW general forum about whether flasking/gemming for stamina is a viable option for a healing priest in progression raiding, I got thinking.
I just got my first offspec T10 setpiece, and when I put the spellthread on it it struck me that that +20 spirit as Disc is really a waste when I'm already very very close to just getting rid of some mp5 and Intellect gemming as progression demands it and as I have less and less mana efficiency concerns. The only other option is going for Stamina and I talked with my GM (he's one of those crazy top 15 ranked healers) and he agreed that Stamina is actually better than a tiny amount of mana regeneration that I virtually never need (and if I do I can just swap in my other T10 legs with spirit gemming 'n all) for the bosses we're currently progressing on. I'll go with it and see if I like it and if it makes me die less (as if).
So Moz, thank you for making me think about my choices a bit more.