Dear tanks in PUGs,
I realize that heroics are serious business. Honestly for me they are, I've been to Naxx only once, for once boss and some trash. Where was I?
Oh yes, heroics are serious business. However if you're uncrittable, nothing (except maybe that damn dinosaur in DK) will hit so hard that your effective health is an issue. You will survive the next hit, and the next, and the next. I could not heal a decent tank for probably ten seconds, on a boss, before it was a serious issue.
What I'm trying to say is that gemming for stamina is not the greatest idea. Get some damn avoidance. I don't care if I can not heal you for 20 seconds, but then you need constant heals after that because you have 20% combined avoidance.
Avoidance is unreliable, but it averages out well over time. It reduces the heals you need. Get more avoidance!
A Formerly Holy Paladin
P.S. Okay fine, I'm almost never holy, but I enjoyed it for a while, until I got sick of tanks that needed way too much healing.