Making control of lands more efficient with multiple kingdom than with one giant kingdom. In other word, nonlinear upkeep cost for kingdom.
I dislike this idea and it leads directly to what I have been writing about in the OP-post: people making two or more badly-maintained kingdoms. Right now, the trend is set so that having no or small number of statues and covering as many people as possible benefits most.
[*]Large kingdom has more benefit for member than small kingdom
[*]Large kingdom is more powerful than small kingdom
[*]Large kingdom is equally as efficient as small kingdom
You are confusing factions with kingdoms there, imho. Kingdom isn't a separate entity from a faction. If your faction is strong, ordinary villages cannot compete with it. Same goes with the kingdoms.
If you'd take the situation when 1 equally strong faction got smaller kingdom than the other equally strong faction, then the first faction can make it's way by challenging the enemy kingdom's cheirns, attracting more people in, trading and etc. with enough effort. At some point, there is no difference whether you've got 400k authority or 250k stacked up for land-fights.
The best way to make people to look after their kingdoms and keep them small is highering the cheirn upkeep (suggested that before, but the devs made a reversive change), not the statues. That way people will be overcrowding boosted kingdoms and move to other kingdoms with more lands but smaller buff.
I am looking at how this system scales into future, not just how it work now. I agree that now there is not much competing needed.
Well, meanwhile I am predicting the future from how the players used the system from the start. Claim as much land as possible and etc., have no statues.
Indirectly, yes. It would make it more difficult for a single kingdom to monopolize players.
So, for the sake of some equity, the trades should go stale, the new players should develop slower? I think, that without proper compensational measures such fixes won't do any good.