I love the new way that outposts are captured rather than destroyed. However the system feels like an inferior version of the gal civ2 starbase system. The most eye twitching factor of this is the growth bonus which is infinitely abuseable. There should be  alimit on how many upgrades an outpost should have and on how many upgrades a settlement can support

for example:

conclave: 2

the introvert settlement

fortress: 4

the fortress needs to have supplies carried in and uses the outpost to improve a sovereigns military presence

town: 3

the town will use these to cart in raw materials to fuel growth and the sovereigns economy.

In addition, i feel that this would be a perfect area to reintroduce Capitar into the game. I see capitar as a materials based town and fortress heavy  group that doesn't use a conclave very much. They support a slavery system that was mainy used to boost the economy (as opposed to the military/ magical boosts of you know who). These are a race that have fragile but highly accurate troops so they need the benefits of fighting on their home turf so they like to set up fights near an outpost where they can take adavantage of their infrastructure. There is very much a roman feel to this group.

I think a set up lke this fits in nicely with the tarth background as it explains why tarth likes to make hit and run style attacks against its opponents.

Capitar would get a boost on how many outposts they can support per settlement, its ouposts are self upgradeable (not dependent on building queues), can increase the range of its zone of control, and perhaps they can make an artillery outpost that can attack a certain distance away from it.