From my experience tanking 85 to 89 in leveling gear it has been a bit rough.
My damage is ok, but not nearly as high as I used to put out through out cata compared to similarily geared dps.
And I am getting hit like a truck. Active mitigation should be code for "click this as often as possible or die". My 60 rage ability gives me 45% dodge for 6 seconds. When incoming damage is high I can keep it up I guess about 66% of the time. That is HUGE. If I don't use it, I am taking about a lot more damage then I would otherwise take if I did not have it up.
All this adds up to I am not only using these abilities as much as possible just to keep my healers mana up, I have to revolve my whole rotation around generating rage (by attacking).
Mangle generates 5 Rage when used (or 7 if you have the talent Soul of the Forest). Mangle has a 6 second cooldown.
Auto-Attacks generate 6.2 Rage per attack that deals damage. Your base auto-attack speed is 2.5 seconds.
Enrage generates 20 Rage when used, and an additional 10 Rage over the next 10 seconds. Enrage has a 60 second cooldown.
Critical Strikes of either Mangle or Auto-Attack will generate 15 Rage.
Lacerate. Thrash, or FFF has a 25% chance to reset the cooldown on Mangle.
My tool-box abilities do not generate rage so they directly reduce my 40% dodge uptime. Stuns, charges, knockback, interupts, inervates, swipes, and more all don't give rage and so become very undesirable if a mangle is up, which it almost always is.
Anyways thats my QQ, maybe when I get more crit it will scale better but so far I dislike bear tanking in MoP a lot compared to Cata.
The idea is that they nerfed the shit out of your passive dodge and replaced it with the situational dodge/heal. I agree it is a lot of micromanaging but it will really separate excellent tanks from just mediocre tanks.(Or bads)
The changes you have mentioned is why bears need crit until we are crit capped. All of the math is done out there, but essentially we do not gem agilty anymore, it is stamina/dodge/crit for now.
Our cata damage was 'too high' (We scaled too good w/ agility) and the class was 'too easy' (supposedly) so all the whiney prot pallies got their wish. -- Here's the final bullet, to put our love to death.