Pardon my ignorance, but does the gem stacking for Pre-Tier 11 raid essentially look like a stam stack, like in Wrath? I ask because the "bear guide" on MMO definitely suggests stacking expertise gems prior to stamina.
Many players are advocating stacking stamina while healers are struggling to heal, simply because this offers more cushion for things to go wrong. However, at a reasonable health pool from gear, it is much more important for tanks in general to ensure they are at (or at least as close as they can get) to the hit and expertise caps in order to maximise their TPS as well as make sure taunts never miss. If you miss a taunt on a mob attacking a healer then it doesn't matter how much stamina you have
Also, the discussion is raging on back there about dodge vs. agility. Are the added bonuses of agility worth the slight dodge loss?
I've been looking at the benefit of agility vs dodge as well as the benefit of agility vs stamina.
Essentially, dodge gives mitigation only and doesn't benefit from kings/motw. On gear alone the dodge% from the dodge rating will never be as high as what you gain from agility, which means reforging and gemming is the only way to benefit from increasing this which I feel is giving away too much because of the extra benefit of agility and losing the stat you reforge with, but there should be some hard numbers to back this up somewhere to give a definate answer.
As for stamina vs agility I think many overlook the benefit of agility. While stamina is great at the start as I said, it lacks the bonuses of agility. Extra health will grant AP from Vengeance, BUT, agility will net you greater AP and more importantly have constant uptime compared to vengeance needing to stack (and dropping off through mitigation). This results in agility giving more consistent mitigation from Savage Defence than stamina will. Agility will also net more AP for threat as well as increasing your dodge for mitigation (see previous post about agility vs dodge though) as well as increasing your crit chance which effectively increases SD uptime and mitigation from this.
All in all I think it looks more beneficial overall for agility stacking rather than anything else since agility effects multiple stats. Save for specific fights where extra health pool may be a better option, agility seems like it is more important than ever before for bears.