Been playing my Feral Druid on PTR and I think something that needs to be looked at is that Savage Defense is going to be scaling way too well in Cata, perhaps giving Bears a huge lead on other tanks in damage mitigation.
In WotLK: Savage Defense only scaled with one thing, AP.
Now in Cata, as a bear gears up;
1) AP values will scale up.
2) Their Mastery lets this ability scale even more.
But especially this:
3) With the new tank passive, Vengeance as raid bosses scale up the damage, druids Savage Defense will be much much stronger, especially with their high health pools.
They said Vengeance was intended to give Tank threat and DPS a way to scale for all tanks, but I think this is an unintended secondary benefit only for druids.