As for Core turret controllers... sad panda. They still force you to do with them what they are meant to support (Aka more distributed defense to buff said defense ).
My advice to you, specifically, is to forget any irreplaceables in the game exist, including core turret controllers, unless you happen to be playing against two Chivalric AIs (which I designed with people like you in mind, have you tried those? They don't protect from minor faction ships, but that can be mitigated). From our conversations I'm convinced that you will never, ever be ok with irreplaceables that cannot be placed behind a chokepoint
Not sure how new re-balance will affect that.. they might be able to defend themselves if you get enough of them
Consider for a moment:
1) Turrets are balanced at roughly 3x the effectiveness of fleet ships, cap-vs-cap.
2) There will now be 8 core turret controllers on every map.
3) Each core turret controller enables you to place a full mkV cap on any in-supply planet you wish (assuming your resources support it).
Tell me this: if
120 mk*caps of per-planet firepower is not enough to defend however many of the controllers fall outside your normal perimeter... then what
would be enough?
From another perspective: given that 8 planets on the map will have a controller, how many do you think you can enclose behind your normal perimeter? Surely even 1 would substantially help with distributed defense elsewhere. At the very least, it's likely that you won't need to spend K on that turret type.
did energy costs remain from mk V?
Edit: oops, meant to reply to this but left a gap instead: the energy costs for the mkVs were, and still are, the same as the energy costs for mkI.
Is there any plan for actual per planet turrets any time soon?
These are those, really, because changing the existing turret types to be per-planet is just a no-go for a very large part of the community, unless the turrets were otherwise untouched, which would just mean chokepoint-level defenses everywhere with no exposed bits (i.e. core turret controllers) for the AI to attack.