I'm afraid you only get the XP for stealing the crown jewels then. A fighter would get XP for the killing AND for the quest. Like it is now in Divinity.
Unless they changed this for Riftrunner of course. As far as I heard there still are no XP bonusses for avoiding fights and solving quests that way.
Then you should only get the XP for stealing the crown jewels and not for the killing. The mission is: steal the crown jewels. Nowhere is the contract did it say "bonuses paid for indiscriminate manslaughter".
