Sorry to spam out suggestions right now, but this is the last one for now I promise.

the outpost upgrading mechanic- I don't think it's very fun, and it's leaning towards micromanagement hell.  I think it needs to be reworked some but not completely.  I'm basing my opinion on the fact the outpost upgrades are very powerful, yet enough of a micromanagement chore that I don't bother with them.  (and does the AI know how to use them right?)

My suggestion here may be a bit too much work right now, but here's what I'd think would be more fun.

Outposts: keep the outpost flipping that you introduced, that's a great change

However: instead of building specific buildings, outposts should have levels. 

The level of an outpost would be capped at the level of its associated city.   Outposts also increase the unrest of a city by the sum of their levels (to prevent outpost spam)

Level 2 outposts gain militia to defend the outpost if it's attacked by a monster or army.

The benefits of outpost level gain, will be determined by certain techs, and the resources in the outposts's ZOC.  Cooperation might increase the size of the militia, weapon techs would upgrade weapon, Drills would give bonuses to unit stats, sorcery would give a crystal guardian if there's crystal in the ZOC.

Level 3 outposts with a shard might get a shard tower that shoots a spell x% of the time, as another example.