Oh if I unlocked logistics it would be to go everywhere. It's my favorite of the command stations for quick strike/defense capabilities, etc. that said, does its slowing stack with gravity turrets. The fact that those unlocks do actually help the home station was just an extra incentive 
You only get 6 of the mk II stations. They're not going everywhere.
I don't know if the slowing stacks.
For serious defense, IMO the Military stations win. It's hard to beat translocating engine damaging (paralyzing on mk III) shots, tachyon coverage (large on mk II, planet wide on mk III), and the attack boost for everything else in the system. Double fun when the AI sends raid starships and the station's shots keep pushing the ship away, so it never gets to close in to attack.
