I just updated to 1.5, I'm really loving it. The ship upgrades are really interesting.
I feel culture centers could use a bit of love (did you add the "Wail of the sacrificed" population-bomb Advent ability? If so, kudos, it's a really interesting and well-thought out ability), say psudo-espionage or propaganda.
Aw, I like his missile equipped Celio. Besides if I give him a new cap model someone else is going to need to get a cruiser. And I don't think Aurelion or Deyrenov will appreciate that very much, even if Kol outranks them.
I found it a bit odd that "Admiral" Kol didn't get a Kol battleship... just felt wierd that the one "named" guy is in a puny cruiser.
For wormhole, what about a captureable structure like the Kostura Cannon? Description: This ancient structure can utilize the wormhole next to it, and will instantly create a phase lane for your empire between this gravity well and another one you would like in the galaxy for some time.
What about spawning some sort of reinforcements, a la the Dark Fleet? Of course who's to say they would be friendly...
Basically, something with antimatter, black holes, or teleportation/warping.
I actually already had an idea for that. It's not quite that economic but it should be pretty cool, especially if you like the pirates.
In addition to the base itself, what about making pirates have a chance at resurgence? Perhaps you could add a buff so that, upon the base's destruction/fall, there'd be a chance of raiders spawning in the grav. well to try and reclaim it.
Another thing: pirates are mainly about raiding, right? Why not have them spawn separately along trade lanes?
So, what if you put a passive on all trade/refinery ships, that places a buff on grav. wells they pass through. The buff would then (based on conditions and stuff, like a bigger one for neutral/uncolonizable) have a chance to spawn temporary "pirate" raiders.
You could even have a research "upgrade" "anti-piracy measures" that would reduce the spawn chance or something.
I tried something similar with "sabotage" with factories and extractors; I gave them a passive "sabotage" ability that, every 2 minutes or so, would have a 1% chance to deal moderate AoE damage and/or disable the structurealled "sabotage."
I thought that the culture centers seemed like good buildings to use for "espionage" type stuff; in the prioer case I added the ability to stack the debuff on enemy planets in the same solar system (there's a constraint for the target planet being in the same system rather than just explored; I figured it was better to limit it to same-system for balance/gameplay reasons).
Plus a couple research topics to reduce the sabotage chance/recurrence, and a few unrelated abilities (propaganda- sort of like a weaker in-system Deliverance) and combat buffs, battle meditation, e.g. "Extra Comm Channels" or "Battle Meditation" IIRC Rebellion added new conditions/ability modifiers (for the new cap ships' stacking abilities) that could check for specific buffs/debuffs.
Maybe they could even spawn rebels in a gravity well (would cost money, perhaps?) to cause additional problems.
This mod is in sort of a bind with things like 24 Starbase slots though. On one hand I started as mainly a single player modder, and as a 4X mod obviously there's some focus towards the big, longer games. On the other hand, lately I've done more multiplayer and understand the competitive scene better, so I try to keep my mod fairly balanced and fix issues with the Vanilla imbalances where I can. On one hand I like the restricted slots, as it forces you to make a strategic decision on how you want to use each starbase, and its probably not economical to ever use all 24 upgrades on a SB even if you could. On the other, I know a lot of single players like to turtle, and in longer games it might really be useful to have more than 8 slots. I don't know if I'll do this but if I do it will likely be as a minimod, which I've done with things like Superweapons and titan levels where what is best for one style of play contradicts what is best for the other.
I almost always get at least one weapon, hangar or toughness upgrade whenever I build a star-base (unless it's way late game and I'm just building trade stations or planning for a backstab invasion a la WWII) as a matter of course. I dunno, I just feel that it needs at least one of the upgrades to hold its weight in a major assault; hence one of the first changes I modded was to increase the base hangar capacity and subsequent upgrades, so I wouldn't have to build a hangar for a SC garrison.
Maybe increasing the upgrades to 9 or ten, or (pipe dream) adding additional weapons i.e. point defense or otherwise making them a bit better out of the box and/or a bit tougher at full upgrade capacity.
It's not that big of an issue, though. 8 is enough to cover most of what's needed; there are times that I feel pinched between a planet's logistical or tactical slots and a hangar/trade upgrade, but then again that's how it should be.
I trust your numbers a hell of a lot more than anything I'd do.