On my main playthrough I've been focusing on combat prowess, for when we inevitably get into fights
That does make sense. However, in my experience in most game with different outcomes that are not just plain pure combat games, charisma is the most important skill as usually getting the best endings imply influencing people.
To be fair though, I doubt that the skill system in this game is going to be anything different than "if you have this skill, the solution to this part o the game will be like this otherwise is like that" and will most likely don't have huge repercussions. There are only too many paths in a tree you can make before it becomes unmanageable.
Also, so far picking between charisma, combat and stealth only happens I think the first time you feed with Sharon. And if I became a vampire, I would follow Sharon's way of feeding. Not only because for me is the one that makes most sense to survive as a vampire, but also because I would follow Sharon's advice as close as possible, being a total fledgling and she being the only nice one taking care of me.