From a roleplaying standpoint, convincing a guard to let you pass is more fitting for a good char while the double reward (charisma XP + kill) doesn't make too much sense. But on the other hand you don't want to give the players the same reward (XP + gear) for a game of R-P-S (charisma can be maxed out without even investing a single point) as fighting a dozend guys that are above your own level. Also what if you choose the peaceful solution, but still want to pickpocket them/ see what is in the chest in their base and get cought?
