I mentioned previously (though it very well could have been in another thread) that we have been looking a lot at tank balance. We think tanks surviving short windows of spike damage has been fairly balanced in beta for some time, and indeed we are seeing all tank classes used effectively in beta Challenge Modes and Heroic raid testing.
The rage tanks required too much healing, so we are causing them to take less damage and have more rage for active mitigation.
-- Rage generation from Revenge increased from 10 to 15.
-- Rage generation from Shield Slam increased from 15 to 20. (Sword and Board continues to give 5 extra, so 25 now).
-- Reduced internal cooldown on Critical Block from Enrage from 5 sec to 3 sec.
-- Increased damage reduction from Defensive Stance from 15% to 25%.
-- Increased armor from Unwavering Sentinel from 10% to 25%.