Stamina is just for looks, resilience is what really matters when you are being nuked and healed...
When you're 2000/2500 instead of 1896/2380 you're thinking kinda cool, I still have more hp than I would have with BoA trinket... Stamina owns!
When youre nuked for 2k damage with double AGM and simultaneously (did I get that right) healed back for 2k damage, you would be 2000/2500 again. With BoA trinket, it would be 1963. This might not sound so awesome, in fact it sounds kinda bad compared to AGM.
Now if a rogue can easily do 2k damage in around, lets say 20 seconds, maybe faster, I don't know but yeah, lets say a rogue does 2k dmg in 20 seconds. Now there are 2 rogue against you and your healer in the roof, you have no dps and they don't seem to be dying too easily and your offence is slacking and not doing shit. So they stay there for 3 minutes pounding you continuosly, that's around 15k dmg. Now the BoA trink has already deflected around 600 damage so I'd say it's kinda comparable to agm.
Depends on situation, if you're a druid fc and are good at kiting at tunnel roofs etc, you might just wanna switch to agm when trink is on cd since you're not gonna get nuked down anyways if you're good, unless you get ambushed by 3 rogues at the same time or something, in which case stamina is pretty vital stat to have.
This is just so you can compare where it is wiser to use agm and where the boa trink. (inb4 "tl;dr lulz agm is betta get ova it scrub")