We got a Backdoor Hacker AI once and selected two worlds next to each other (one of mine, one of my partner's). Sadly, our defense system was inadequate and one of the home command stations fell (to three raid starships III which came with Exo-galactic Spirecraft wave - I put far too little gravity turrets on that planet).
I'm surprised there's so little about logistics stations; I'm a big fan. Even the Mk Is affect the whole planet, whereas military Mk Is need to have ships entering a pretty small range. More importantly, they make turrets and fortresses more powerful by keeping ships in range longer, I find this adds a lot more firepower to a big battle than a military station. But I haven't tried upgraded military CCs.
They're great on "bottleneck" worlds that have a few ways into your territory and you can't just slap an FF over the route home; they make it harder for AI ships to dash across into your core. They're also good on new border worlds --- if you put them right at the edge of the map farthest from where attacks are coming in, you have tons of time to bring in reinforcements while the AI ships are flying out to find your command center.
There's an issue that hasn't really been addressed concerning exogalactic forces and gravity effects. Basically, if a Spirecraft or Golem ship is selected as the lead ship for a strike force contingent, then the speed-linking system used to keep the contingent together essentially makes the entire contingent immune to gravity effects. This is a major problem with logistics stations if you're playing with any kind of exogalactic strike forces enabled (and why military are superior for this), and it's why gravity turrets probably wouldn't have helped your situation, Irxallis.
That being said, this is also player-abusable IIRC. If there's a problematic AI planet with a gravity drill on it, group move your forces with a spirecraft or golem while they're on the planet and I believe your fleetships/starships will ignore the gravity effect. Been a while since I've done that, so don't remember if it still applies, but shouldn't be too hard to check.
