A hero can achieve +4 in command which makes him/her too powerful imo. I know there are some units to counter hero powers but these units are too rare.
Atm, I think + 4 in command is too easy to achieve and probably too powerful as well. I think +3 command should be max from EXP points (and harder to reach than current setup). In addition - perhaps create some rare items (from quests) which gives command (eg staff of ruling) which would make it possible to achieve above 3 in command but still very hard to do so.
Regarding the units in battles in beta2; I think the battles are very well balanced atm (better than beta 1). Most fights are between 1-2 turn units though so hard to evaluate all aspects. Perhaps some tweakening is required for 3 turn and above units.
Perhaps start with reducing the prices to buy +3 turn units (and above) slightly
(as gold income got a nerf since beta 1 as well
I am having fun atm.... keep it going