The default Size for Hit Points… the calculation I use now is: The square root of the weight = SIZ Constitution x SIZ/10 = Hit Points So, a person with 270 pounds has a Size of 16.4. with a Constitution of 12, the Hit Points = 12x (16.4/10) = 12 x 1.64 = 19.68, round down = 19 Hit Points.
Resilience is equivalent in function to Hit Points, but not mathematically aligned in any way as Resilience measures different things than Hit Points.
Yes, a unit can have a Size modifier and a different Damage modifier, but it would be rare. It would be rare because I wanted the Size to be somewhat of a constant, and the variablity to be in the Offense and Defense. If that different modifier is the best way to model something, go for it.
I don’t really go for having balance in matchups, since I rather think asymetry helps to drive scenarios and victory conditions. But, yeah, an ATGM team will absolutely devastate a mob of people. This is why dispersion in modern combat is essential, so that you can minimize the amount of people caught in the blast radius.
I made a lot of changes since the first versions were posted, so I uploaded the new versions.