Honestly I think a simple solution is to just try and give nonviolent solutions an equivalent amount of EXP for killing everyone in the encounter. You should be able to roleplay how you want and think with your head for the smartest/best solution. Sometimes that might involve slaughtering everyone, sometimes it might not be fighting at all. You shouldn't be objectively penalized for not killing everything that moves.
You are not penalized. Several posters have in fact demonstrated (in game) that you get more experience by not killing everything that moves. So this is a non issue. The current debate revolves around the concept of double dipping. i.e. getting the quest exp (more than you would by just killing) and then killing the guys.
