I think the four army quantity is against the balance of the game. I think it a goog idea, but I feel it unbalanced at its present state.
See my problem: When you are going trough the techtree, you are receiving better equipment, larger army size (from 4 to 9), and larger army quantity (3/5/7/9).
These changes would make a difference alone, but together they boost too fast the player's advantage. I dont think the AI to be able to exploit this opportunities properly or immediatelly. So I can have a super army which can devastate the AI's smaller and less equipped armies.
For example when you train a group(5) instead of a party(3) you double the size of your units in an army. For example when you reach logistic you can have an army with 5 slots. The prior army (with 1 hero and 4 party) consist of 13 units. The army with logistic can consist of 21 units (1 hero, 4 groups), but after +1 army size 26. And I didn't mention the difference in quality.
So the first army has 0 percent chance to make a scrape on the new. (Ok, its hero can.)
I think the quantities could help a bit to avoid the sudden maxarmypower-jumps.
Presently we have: party(3), group(5), squad(7), company(9)
But what if:
5/7/9 - the problem with this could be the necessity of the full early game rebalance because of the larger army size
4/6/8 - better than above
4/5/6/8 - I think this the best (not large jumps, but its worth to develop, depending on playstyle you can skip 5 or 6)
3/4/6/8 - similar to the recent setout
4/5/7/9 - if we want 9
So these are my ideas . . . opinion???
(and excuse me for my bad english)