One of my only complaints with the new version is that you aren't rewarded for beating dungeons with different classes. I was trying to come up with a way to implement a type of bonus like the alpha had without completely breaking the game. And then I had an idea so crazy it might just work...
Make the power of the Vicious reward items (Dragon Shield, Avatar Sigil, etc.) correspond with the number of classes you've beaten the dungeon with. For example, the Dragon Shield might be 20% resists, with a bonus 1% for each class you've beaten the boss with. Namtar's item could affect the health penalty (maybe even eventually turn it into a bonus) and the Avatar Sigil could either have the berserk damage bonus or the threshold affected.
On a slightly related note, if the locker code supports it, a unique glyph dropped by one of the vicious bosses would be pretty cool.