I was playing through a game when I encountered an interesting situation. Late game, when you've researched the ability to colonize extreme worlds, you can only colonize worlds that are either in your influence sphere or in neutral space. If you colonize an extreme world in another civilization's territory, it will inevitably be flipped before it generates enough influence to create it's own influence sphere. In my game, I rushed every single influence improvement for the 10 turns given to me, and it still wasn't enough, when my influence planet had 21.8 culture value (or whatever the term is) and the nearest foreign civilization had 6.7 culture value, to stop it from being flipped. This could just be because the game is still in beta, and can obviously be tweaked or fixed if it is not working as intended. I don't pretend to know much about how influence sphere's are calculated, but I have an alternate suggestion.

Give influence flip immunity to colonies if the foreign civilization trying to flip them doesn't have the required tech to colonize said planet. I know in GalCiv II (and I'm assuming at the moment GalCivIII, but I haven't tested it) civilizations that don't have the required tech to colonize flipped planets simply can't produce anything on them until they research the required tech. So they're useless to the civilization that acquired them, except in that by flipping them, they deny their use to the civilization that originally colonized them. So basically all it really does right now is discourage civilization from colonizing planets outside of their influence or neutral space, which overall devalues the ability to colonize extreme worlds. Especially in late game, when a majority of the map is under influence, which also happens to be when you tend to research extreme colonization. Giving extreme worlds influence protection would not only encourage it's research, but create new strategies by allowing colonies to thrive in foreign territory, and eventually build their own influence spheres. The lore could be justified by having the controlling empire threaten to cut off supplies to the extreme colony, or to pull out with it's technology (i.e. the colony is dependent). The influential empire can not take over because it doesn't have the means to successfully run the colony.

Whilst thinking all this up in terms of culture flipping, I also considered invasion. I'm assuming again, that when an enemy invades an extreme colony and does not have the tech to colonize it, that the colony is useless to the invading empire. I suggest that extreme colonies, when invaded by an enemy that does not have extreme colonization tech, be immune to traditional invasion. An empire that does not understand survival on extreme worlds should not be able to fight on one. Instead, the only invasion options should be things like orbital bombarding or tidal destruction or whatever special invasion tactics exist that do not include troop ground assault. Further, a successful "invasion" should render the extreme colony uncolonized again, instead of conquered, since the invading empire does not have the means to maintain it.

Both of these suggestions would remove the whole awkward controlling of a colony that is useless, and make it more desirable to research extreme colonization techs.

That's it. Sorry for the long essay. Keep up the good work.