I agree the xp split seems kind of harsh, but I do acknowledge the attempt to limit stacks of doom. But if I top out at level 9-10 for most heroes on a large map, why then can I recruit most heroes at lvls 7 & 9...??? If they're pretty much top level at that point I should have to develop them to level 9 not just hire them at that level. I suggest nerfing starting hero levels to 1-2-3-4 not 1-5-7-9....
Additionally I would agree that a stack of doom is a group of heroes and maybe a few drakes leveling 9-11 each. I took out every unit and quest with such units dresses for the most part only in chain mail and quest reward items & weapons using magic and combat mixed. I also had no enchantments on my units, unit the last battle with the dragon dude that I had to equip & enchant for and then I wrote him off in a few turns only loosing 1 hero.
Also the fireball+10 initiative skills are tooooo easy. This should be adjusted... not sure how. 2nd game I took this combo and my Sov is walking through enemies with very little effort... Can the starting positions of enemies be spread out more instead of a nice 3x3 fire ball eating clump? Then I'd only toast 2-4 instead of almost all the opposition in 1 cast.
This would also address the issue of hand to hand units being behind archers at the start of combat as there would be space to pass between instead of all the way around, or stuck in the center of, the archer units.