I think what's "worse" (relatively--I don't see this unequal XP gain to be a big problem) is that in a number of cases, you get more or less XP depending on the dialogue decisions made. EARLY SPOILERS FOLLOW
For example, when you help out the 2 lighthouse Legionnaires and they report to Aureus, you get more XP for playing along and letting them go home versus revealing the truth that you cleared out the undead. Another example is Tom, the brother of that maid in mayor Cecil's home that you discover was killed in the cave. When you lie to her and tell her he's fine, you get more XP than if you tell her the truth. These are more questionable in my mind, because it's not a huge difference in what you did (kill vs. talk your way past), but a decision of how something is told.
In that first scenario you do get +1 rep for telling him that it was you who cleared the lighthouse. So with meta knowledge it's +1 rep vs some extra exp.
