Kaleekanoka said:
So if I got this right; to have more units than you are allowed to have only effects the amount of gold you have?
Yes, for each unit above the free-upkeep-limit you have to pay one gold per turn in upkeep costs. (In the conquest expansion this is changed to 2 gpt for republic, but republic gains 1/3/4 free unit upkeep in return)
The limit is 0 in republic, so all units are above the free-upkeep-limit.
You can also look at it as a type of gold that can only be spend on unit-upkeep or be wasted, but is not effected by corruption.
So if you have a size 12 city, assuming no corruption, and assuming you put a road on every tile that a citizen is working on, this city will yield 12 commerce.
Under monarchy, you get a 4 gpt bonus, but those can only be spend on unit upkeep. If you don't have 4 units, the 4gpt bonus will simply be lost.
Under Republic, you gain 12 commerce bonus for this city. This could be turned into 12 gpt if you set the SCI slider at 50%, the (assuming no happiness issues) and 18 gpt with a market. So the same city could pay the upkeep of 18 units under republic! 4.5 times as much. While still sending turning the same amount of commerce (12) in science beakers.
And if you have no need of 18 units? then you can up the SCI slider and the bonus will become science, and is not lost.
The catch is that the republic bonus is effected by corruption. so in the end you don't exactly get a 12 or 18 gold bonus in every city.