I'm not sure about the "Barb will lose without War Cry no matter what" statement, but it does seem unfavorable for sure (especially if they Barb isn't using Unforgiving). Next, I too use enough EHP to survive a few critical Rends, but it really hurts my discipline a lot since I am non-legacy. I usually don't have discipline problems unless I am playing sloppy and getting Rended too often or if the Barb is extra aggressive and forcing me to Vault excessively.
Mystical has several equipment options in US server. He can attain my EHP but less DPS than I with his tanky gear but he wins due to discipline management (neither of us can 1-shot the other), or he can attain almost my DPS but less EHP with his more offensive gear (he wouldn't use that against me though lol).
If I use my tanky gear and perfectionist with 70 max discipline (i.e. 110k HP, 700-800 all resist, 5k armor, 200k unbuffed dps), I don't think I can kill some Barbs (maybe like yourself) but I sure would be really annoying to kill! I prefer to duel in a manner where both sides have a chance to win, not where neither side can win.