You are shafting yourself rather hard by having two champions in one army, I believe. From what I've seen, the exp the regular units in the army receive is 100% divided by amount of champions, then halved. Excluding modifications like traits and talents, if a monster is worth 100 exp and you got two champions in your army, the regular units will receive 25 exp. 100 divided by 2 = 50. Half of 50 = 25. Hope that clarify it for you 