@Keith: I think we (being you and me) are now talking about two different things (if related).
On your questions:
1) If you have the power and position (including CSGs, if on) to kill the AI, would you ever take another planet?
Depending on how you define position, sometimes yes. I can technically be in a position to stomp the AI, but my defense is so weak that the AI's response would kill me before I can turn to take out the second AI. This would be rather uncommon, but it does happen to me due to how I planet hop out my forward bases.
2) If you do not have the power and position (including anything non-AIP increasing like hacking) to kill the AI, would you ever not take another planet?
No (err, yes?). By this I mean that if I don't have the strength needed, I have
to take another planet, that is the only way to make my fleet stronger. I could K-hack a system or two I suppose if there's only a small strength difference left, and I might delay taking more planets to deal with something like a CPA, but I'm going to need more planets before endgame.
@chemical_art: On power curves, my original contention when I started this thread was that the power curves are fine, progress along them just happens too fast on both sides, so I posted this as a method for slowing down how fast the 'power' of each side escalates.
On the starting K, I never actually stated it outright, but I was assuming that would get knocked down by 1/3 also to keep things in line.
If Mk III fleet ship costs (and some of the turret costs) get reduced as is being talked about in another thread, dropping starting K from 10,000 to 7,000 should not be a big deal.
@Keith (again): It sounds like this is something you are actually seriously looking at. However, before committing this to a patch, can you post the changes exactly (as in, copy-paste from what the patch-notes would say?) as I don't feel anyone is really on the same page here.