My personal findings thus far, is that no matter whether you gem stamina(which we, as a community of tanking Druids, are mostly against), you can still get through normal content.
When Adept was world first heroic earlier last week, I checked their druid tank; BOOM, all stamina gems, reforged for expertise/hit. Zero dodge reforging.
What's that say?
Means that it makes a small enough difference that with good players around you, whatever you do, you can succeed. However effective it is compared to the other strategies isn't as huge a difference as we make it out to be.
If you check out the official forums, there are quite a few of us that wield the torch and try to bring good information to the masses, however drowned out it is. We had some very very very good discussions on the official forums over the past few months about avoidance, and we realized it would be a very good stat for bears in tier 11 content.