I noticed "feature", if multiple hero units present in same group, amount of XP from combat drop significantly, 5 hero party will get 1xp from nearly any combat, single hero and 4 units get 30+ each.
This "feature" basically enshure doom of any champion - soulsteal, ever if no spell trait present.
Cant see any reason for this, heroes shoud be superior to normal units, but current implementation basically force player to keep only single hero per squad.
At early game, when you get 3 heroes fast, they all doomed, keeping in same party drain XP, train new party - no gold income.
Weak wilndess groups are gone, all medium or strong.