Does convalescence stack with defiance?

[TheodoreMcIntyre]

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I'm not 100% sure what "is faster at 100%" means.

Anyway, Defiance means greater damage reduction from Stoneskin and Adloquium and gives greater healing from Lustrate, so feel free to use Conv. while you have Defiance up. You won't be wasting it at all.
The stoneskin and Lustrate thing is fairly straight forward, more HP means more Stoneskin soaking and healing, respectively.
The max incoming healing bonus a WAR can have is +72.8%, while a PLD can only have +56%, which means a Scholar that casts Adloquium for, say, 1000 HP, a WAR will get 1728 points of mitigation, versus PLD only getting 1560.
That's not taking into account Shield Oath, though, but I'm not really sure the order in which defense buffs vs. shields like Stoneskin or Adloquium are calculated, so.