I realize this maybe an RNG thing, but in the fights where I favored SD, Healers spend a lot of time on me, which they didn't when I used FR. This time was then spend healing the raid. I agree on the boring fight part. (Though, seeing as we are a pretty casual raid, people do make it interesting by not avoiding stuff.)
The thing is Total damage reduction is not a good metric for tank survivability, it wasn't in wrath, and it wasn't in cata, and it still isn't in MoP.the Bleed may be the main source of damage in that fight, but it in and of itself is not going to kill; its what 30k DPS? at least 10 seconds of no healing before it kills you. Each dog hits as hard as morchok HC did. It's not a tank survivability fight. even without active defenses we're looking at a good 5-6 seconds of taking it to the face before we keel over. Its a don't stand in stuff whilst the the tanks juggle mobs fight. Its a boring fight once you learn the mechanics.
I don't quite understand the data you seem to be working off of. It's possible my understanding is flawed. In one of our kills, I used FR exclusively since it made our healer's life easier. In that fight, Rend Flesh gets refreshed every six seconds, with the occasional skip to 12 seconds (meaning I dodged the meele attack). With a 15 second duration, that means I either need to dodge the initial attack and every further attack six seconds later to avoid the application completely, OR dodge between two and three times on demand to allow the bleed to fall off and then again every six seconds. Granted, I have been stacking mastery and capped hit and expertise (soft) instead of dodge, but that seems a rather risky gamble considering I could spend all that rage on heals to counter the bleed and some meele damage on top of it. (Of which, admitedly, I take more.) The long and the short of it is, that in every attempt we had, whenever I used SD in favor of SR, our healers had more trouble keeping me up and more importantly, spend time healing me rather than healing the raid. (We did have some bad luck with our combos though.) Now with better gear, maybe I should give SD another try.
You only need to dodge two in a row for the bleeds to come off, and then every dodge after that keeps it off. Managed to dodge a few times in a row after having it fall off and spent 37 seconds bleed free, which isn't a 'lot' for a 7+ minute fight, but I'll take saving my healers 1.4 million in damage to heal any day.
I gotta admit, I mostly miss bearcatting, but I fully recognize Blizzards reasons for removing it. I used to enjoy trying to maximise my Threat and DPS while still tanking and managing my defensive cooldowns. A large part of this was Maul, switching to cat for a few bleeds etc. Now that losing your rage hurts so much, I find myself not doing this at all.
At least three of the tank classes (Warrior, Druid, Paladin) use the binary 'this or that with defensive resource' choice. I can't speak on monks or death knights, but those three got that as their Active Mitigation mechanic. It's less boring than not needing to worry about choices at all, I suppose, and we didn't lose a lot of spells, so may I humbly ask what made bears more interesting to you pre-MoP that you're missing now? Or is it that you see that other tank classes have more buttons/functionality overall?
I do have more buttons to push on my other tanking classes, though a large part of this is due to the shapeshift mechanic. As long as we are actively tanking, a lot of our abilities might as well not exist which is not the case for most tanking classes. Case in Point, our raid loses my raid CD (Tranquility) completely in the Stoneguard fight, simply because its unusuable in bear. A DK can still use chains of ice for example, but my roots and cyclone are unusuable. (Asside from NS)
I do realize this could be a "the grass is greener" thing, which would mean I created my first whine post without wanting to. In which case, I apologize. It's that the "active" tanking feels a lot more passive because I press the same buttons over and over. When I tank on my DK, I find myself trying to judge exactly when to use Deathstrike, when to dump Runic Power etc. Its reactive to the unique conditions of the situation.
On my Druid, I just press SD whenever I can unless I know a cast or move phase is upcomming or FR when not tanking (or tanking Stoneguards). It feels scripted: "Do x until 60 rage then press SD". I do generate ressources and spend them on FR instead of having passive dodge, but with few exceptions, there is very little reason not to press SD once you have the 60 rage to do so. I find it hard to properly express this, but fishing for SD procs in Cata kind of felt more active than waiting for mangle procs and the 60 rage to press SD. I realize this a feeling and not a hard fact.