While I'm posting, I'd also like to bounce my thoughts about savage defense off the people here. I'm sure that this is not a groundbreaking statement, but I think that SD is the worst mastery of the tanking classes. I believe that it pigeonholes bears into a permanent OTing/add role because of it's inferiority to block and massive death strike shields. The solution to this would be to revert one of the two changes that Blizzard made to SD from Wrath to Cata, either give us the chance to proc on periodic crits, or turn it up to 65% base. I prefer the former of these, as a more consistent shield would give us a more block-like mechanic, instead of the sudo-block that we have now. While i'm sure that the math on sims don't back up my feelings on the matter, and most bears have come to accept SD in all it's glorious inferiority, watching SD uptimes/absorbs compared to my warrior counterpart's blocks is pretty disheartening.
I agree, that SD is the worst Mastery, but what we lose out in some fights, especially fast hitting block-able encounters we do make up with a couple things.
1) more armor, I have about 9-10% more damage mitigation from armor than our other tanks
2) higher avoidance via base dodge talents.. although its not the difference of WOTLK, and I ahve not compared the difference since the agility/parry changes for plate tanks since 4.2
3) more passive reduction on all attacks, 18% with NR, that is is 8% more than other tanks
4) arguable the best magic resistance in non-burts fights.. 24% passive reduction on fight with constant magic damage like Bethtilac, Rhyolith, and Ragnaros
What sucks about this is that it makes our damage mitigation all passive, and lowers the skill required to play it well compared to the other tanks. It was great when I was raid leading, because I could focus on the raid vs my survivability. Now that I am not leading anymore, my bear doesn't feel very interactive, although still very capable.