It was really stressful for healers. At least for me and Iir, I can't say about chemic. Because the fights seemed to last for ages, and both of us were having constant problems with mana. A problem that I really haven't faced in Ulduar (except when I had worse gear and no mana trinket). And i really can't focus on mana regen more, because the heals needed in ToC are massive. Although I already have a few ideas I'm gonna talk to the healers about which should help us conserve more mana. And yes we really did miss a priest in most fights, so it would have been awesome to have Holykitty with us.