Yesterday I was doing some favor runs with my lvl 14 fighter, along with a lvl 15 sorc friend, and we came across 2 quests.
1. Reclamation: lvl 11 on hard (we could not open elite) = 0 xp
2. The Graverobber: lvl 9 on elite = 3,000 xp (including breakables, mobs killing and 1st time completion bonuses)
How could that be, a lower lvl quest actually giving xp when a higher lvl one did not? I have not repeated the first quest in order to cap or decrease my xp (I don't even like Ataraxia's quests so much because they take me too much time and trouble getting there).