I had a very similar idea but it's awkward that you can't cast spells while raging and rage+heal are both things that one would want to access during combat. You also lose base attack bonus by dropping barbarian levels, which in turn reduces your attack speed. I hate that. Boss dps is the one thing this build can consistently do better than others, so it wants as much attack speed as possible. This can be circumvented with Tenser's scrolls or the Divine Crusader mantle but scrolls are a pain to keep up, and the Crusader mantle means you're giving up on the +[1W] from Dreadnought or Grandmaster.