This idea was raised by @Jalily in this thread and I would love to see it realised:
I've always wanted to see charisma have more of an effect in game, and I think those proposed changes would be a brilliant place to start. Anyone have an idea how difficult such changes would be to implement?What if exceptional Charisma gave you more or less leeway as far as NPC reactions to your reputation?
Normally, good NPCs break at 1-2, neutrals at 1, and evil at 19-20. So with 17 Charisma, for example, good NPCs would break at 1, neutrals never, and evil at 20. With 18 Charisma, you can keep everyone regardless of reputation. With 19+, they'll stop using their angry/unhappy lines. :P And with very low Charisma, you'd have to manage your reputation much more carefully to ensure they stick with you.