Secondly, I understand what you are saying about armor/resistance vs. raw stam, however, after talking with all of my healers they still prefer whichever allows me to take the most damage without dying. If the small amount of mitigation isn't more than the increase in hit points, then the buffer the healers have to heal me up in time is shorter.
I will agree that tanks with low armor bother me a lot, and yes, they obviously do take a lot more damage, however this is because they have made bad gearing choices where the choices with armor give a LOT more overall EHP than the stam pieces. In current ICC gearing content, armor is a HUGE contributor to EHP. I think there are only 2 places where someone can adequately and reasonably contend an actual stam vs. armor debate that is realistic, not just theoretical gains (since, you can't gem for armor and I advocate armor to gloves and cloak anyways as per my prot war guide).
I think rings are a great place to make up an armor loss, and the simple fact of the matter is that most of the rings out there with armor, even at lower ivalues (actually all 3 except the devium's ring or however it's spelled are ilevel 245) they provide more EHP than their 264 counterparts. Here my statement of "pick the one with more EHP" holds true again, and it just happens to be a vote for armor (H-Band of the Twin Valks over Juggernaut's band is the main example) so really if people are following my advice they'll be stacking armor here anyways.
The only place where I would say go with stam over armor in a general sense is in trinket selection. Glyph of Indominability is worth roughly 170stam worth of EHP. However, I would recommend The Skeleton Key over the Glyph of Indominability because 1) I think the absorb effect isn't as useless as people make it out to be, especially since it got buffed and it works great in conjunction with the warrior T10 4pc bonus if you choose that gearing route and 2) without considering modifiers, The Skeleton Key is almost 60 stam more worth of EHP. That's like putting 2 gem slots in glyph of indom, or an entire profession worth of EHP better than glyph of indominability. While the tank does lose the marginal benefit of the damage being mitigated rather than needing to be healed, his overall buffer for the healers goes up.
So really trinket selection is the only thing we might actually disagree on when looking at gear.