[thatguy96]

I'd say the type of unit is the best way to play with size in the 4-6 man size range. Since there isn't a rule, its best to look at what you're trying to achieve. As Narwan said, if the unit is more scout oriented, than size 0 is more appropriate, whereas if its infantry then size 1 is more appropriate. The affect on cost between size 0 and size 1 is noticeable as well.