Well, since it's been forever and a day since he hasn't posted and I just came along this awesome idea... here's my two cents or a few thoughts.
Great Idea!
How I think it should be implemented:
Add 3 sliders
1 Global Slider - view able and changeable after Mathematics. Changes default Export / Diffusion of resources - Defaulted to 10%
1 City Import Slider - Defaulted to 100% import (Independent From Global Slider)
1 City Export Slider - Defaulted to 0% export (Independent from Global Slider)
Since Bleeding will be implemented from the game right away and we have all agreed to 10% your cities will automatically bleed the 10% from the global slider. That 10% should go empire wide not just a 10 tile radius. The gold from the California Gold Rush made it to New York city shortly after the rush started anyway.
Example:
City 1 - 10gp/turn
10gp x 10% = 1
10gp - 1gp = 9gp to City 1
1gp to Empire
Empire has 11 Cities
City 1 through City 11
City 1 creating resource doesn't receive diffusion/bleeding from source
City 2 threw City 11 does (10 Cities)
They have there import slider set at 100% as default
So we need some simple math
Amount Resource (from export) Divided by # of Cities (Import)
1 / 10 = .1 to each city
Now depending on the import slider in each city we could run into funky math and problems... so maybe just a on/off switch would be good.
And now with the export slider:
You have a Frontier city that wont be using the resource so they want to export all of the resource into the Empire. Just use the same math except the Resourcing City receives 0 because your slider or switch is set to export all of send resource and your import slider is also set to 0 of said resource.
Also, someone needs to allow workers to create worker colonies (civ3) again and they have a default 100% export to empire marker - as long as they are on the trade network.
Anyway, this way we don't really need workers carrying resources around the map. There should be dedicated units for resource hauling if you need to do a quick boost, wagon trains, urals, trucks.
Thanks guys... hopefully someone can work on the rest of this mod.