I've alway taken less average damage than our warrior, anywhere from 200-700 per hit. Of course, he takes slightly less per hit of Meteor Slash damage, but that's significantly less. Overall I take less damage than him.
After everyone had learned the encounter he was the only one ever dieing from spike damage. We have fairly equal gear levels. He is gemmed pure avoidance, I'm still fairly stamina heavy. I do consider
[Commendation of Kael'thas] a superior trinket in general, but using
[Badge of Tenacity] and
[Moroes' Lucky Pocket Watch] allows having extra avoidance every stomp guaranteed. This could also account for the lower damage since my overall avoidance is about 2% less.