Hello. First I want to say that there is a bug. Groups of 3 people have more upkeep than groups of 5-7, etc.

 Also a difference in the production of very small, if you compare the production of a group of three and seven people.

I also discovered that the basic products of people without clothes are too big. The difference between a force of armor and without armor barely noticeable. It might be worth to reduce the cost of production without armor army? Maybe instead of large quantity of the production, you should use count of the population of the city. It is more logical.  You build a lot of troops in bad armor and quickly ends in the population.

I also do not see any reason to take small groups of soldiers, when you can do more. (An example of a group of 3 or 5 people). Need to fix it. There is a solution. Enter a new rule in the tactical battle. If the two parties are close to an enemy one unit. That two groups have a bonus to ignore armor for example. And it stacks up. While on the other hand, it is not going to help small groups of shooters. Maybe we should give penalties for armor, attack, single units.

You can also add new perks for units like the one of the races. If the army is more than your opponent, you get a bonus for some. But something is to be done. Otherwise, do not see the point in these groups.