The size of an army is too correlated with destruction power.

this economic system worked reasonably well for supreme commander and total annihilation! perhaps if anything, mass is too easy to come by in PA leading to runaway economies in the late game. Really an exponential growth scenario.

SC and TA maps might have 20-30 mass points on the entire map. PA solar systems have seemingly 100+ sometimes.

So perhaps you aren't suggesting a new type of economy? but just a tune of how much each massX gives you?

Changing metal distribution and such is quite possibly the right solution. It also might not be. Either way; I don't know precisely, but it's sensible to experiment with it first before adding new things.

problem with trying to balance as you go.... is that adding more content (which they are going to do) will naturally unbalance the game. may as well keep balance close-ish (without being perfect), finish content, and then perfect balance.

I don't follow, at least once a "standard" for balance has been reached adding new units/content, would only "unbalance" it if the units/content were poorly implemented(in regards to balance specifically) to begin with.

Think of a scale with each side having 3 Apples(6 total), that is the "standard", the apples aren't quite all the same but they were carefully placed to ensure the scale remained balanced. Now say you came along later and wanted to add 4 apples to the scale, seeing as teh initial 6 were carefully placed to ensure both sides were even it would similarly follow that the addition four would also be placed carefully as well. Maybe a couple of the initial apples were also moved back and forth to make sure things stayed balanced, but in the end you still have a scale with 5 apples on each side that is balanced.

Mike