I play a lot of DnD and Pathfinder and this is an extremely common issue in those worlds which, in my opinion, is best handled by giving the same amount of experience no matter what happens. It doesn't matter if you decide to take the direct route and mow everyone down, talk everyone down, or talk everyone down and then jump them while their guard is down, at the end of the day you have "conquered a challenge" and should be rewarded depending on the difficulty of the encounter. The one way that exp should be variable is if there are optional side objectives, stated or otherwise, that alter the difficulty of the encounter or create unique ways to handle the problem. In almost all cases creativity in how to handle a situation should at least be attempted to be rewarded but that can be pretty hard to do without making it feel shoehorned or not comprehensive.
So despite the fact the rules for the game system you mentioned say not to give them the same experience you or your GM do anyway?
The rules also state to punish characters and players for trying to break the game system just because it is a game your GM is nicer than mine and also not a very good GM.
