I'm totally cool with the PvP in EVE. I hope PFO will have something close to that but, here we will have the alignment, and that could make a diference because it might be not so profitable to kill without reason.
The paladin comes to mind. If a Paladin goes crazy and try to kill you for the loot, he might lost all his paladin special habilities, at least, the ones related to auras and spells.