I am still debating that idea...
Bear Tank Comparison:
Gladiator helm enchant:
280 health
-.51% chance to be crit
Defender helm enchant:
-.24 or .28% chance to be hit/dodge/crit
+.85% dodge
As for stats focused towards mitigation, the defender helm enchant may be better, but as for crit reduction... the gladiator helm may instead be the better choice. For a bear tank the 18 stamina is certainly tempting... and the reduced need to rely on defense gives many more options to switch gear around and gain mitigation stats on other items.