Does anyone know the breakpoints for dialogue options based on Int and Cha?

I've found posts on other boards which suggest that 12 in Int and Persuasion Master would cover most (all?) these choices. Is that true?

I can't tell you what the breakpoints are, but I can tell you that 12 INT isn't enough to get the best options in the Ashbury town hall quest, though with high persuasion you may be able to complete the quest with 12 INT. I think 13 is enough to do the trick there, but rather than putting a point into that at that stage I quaffed an intelligence potion to get me the dialog options I needed.