Logistics stations can be stacked with other effects AND slow enemy ships. About the only use for Space-Time Manipulators I've found is to stick them on your home planet, since by default you can't have a logistics station there (which saddens me).
Past that, 30k energy is exorbitant. 15k maybe, but with logistics stations giving speed boost and slowing enemies (heck, the slowing enemies is why I use them instead of military posts usually), I still think I'd rarely use them. What would be cool, for 30k energy, is to give all friendly units on-planet the teleport ability. It definitely conflicts less with logistics stations then, and gives a really nice benefit to go with the mark 2 energy station it'll be consuming per planet you set one up on.