Why exactly would factions need to trade? People would just join a single clan, NORTHERN EMPIRE instead of a bunch of rinky dink clans in order to avoid having to trade at all.
Problems:Single Clan with 70-100+ members or several clans working together with 70-100+ members.
This result in a huge production advantage, where smaller clans and small alliances of clans can't keep up.
And as bad side effect, players who are reduced to farm-bots who then don't really care so much about the game.
Suggestions(in my eyes solutions):
efficiency indicator/multiplicator, so that peak efficiency is reached between f.e. 70-100
You can deal with a single clan easily, the more people the less efficient they work till a point where more members don't bring extra gain(=peak reached).
As you mentioned in another thread, they then just would split into smaller factions, therefor would trade the stuff in between themselves.
Therefor is the Relationship system. Factions with closer relations loose less when they trade with each other, those with neutral or war like relations would loose a shitload if they decide to trade.
Now all would most likely go into alliances because they gain in terms of trade, therefor you would be able to calculate the member count of all who are in f.e. an alliance,
if they reach again 70-100+ members, their production efficiency drops and stays in the level of about 70-100 members even if they would be like 200.
Give them a carrot to join a system, which you then use to regulate the peak size/efficiency/production of HUGE Factions or HUGE alliances.