I only use two stam cause one is the JC with a dodge clicky, otherwise I would of farmed Tia's. Even normal Tia's would be better than the green stam one.
Armor is still awesome. Armor is still sexier than Mastery. Armor always works, it is beautiful.
edit: you need better tank trinkets as the Alchy one + your mystery mastery trinket aren't to spectacular :P
Alchemy one gives me 440 stamina. That alone is enough for me to not give it up. I don't care what agility gives me in terms of dodge, RNG and I have unfinished business, and baby, I ain't kidding (bonus points for reference).
The mystery trinket I was talking about, but not linking, is Za'brox's Lucky Tooth
. I know Mastery isn't all that hot for Druids compared to dodge and stuff (which is why I reforged the mastery on my alchemy trinket to dodge), but it's better than 3k armor just before dying. Macroing the tooth into my Barkskin, I can toss in some extra mitigation every other pull.
Yes, avoidance > health in raids once you have enough health to not die in the time it takes for a healer to cast a heal, but in heroics and such, health is king. Increased Vengeance cap (and thus size of SD procs) and a bigger buffer for when the healer has an aneurysm.
Armor, in my opinion, comes after health in sexiness. Again, this is partly due to RNG hating me. Armor provides constant mitigation whereas dodge is hit or miss. Armor, however, doesn't mitigate magical damage. Neither does health, of course, but it gives the healer more wiggling room to hit panic buttons and such.