RE: Why wont my Kaos spin right
If that is the case that everything as far as the flight surfaces are set up ok, then perhaps the problem is thrust angles. I have found that sometimes "spec" settings for thrust need to be tweaked a bit and that may be an issue. As you have said the lateral balance and CG is checked, and it flies ok for most other aerobatics, so that leaves only other small things that can be an issue.
But the rate of spin is so much different that I wondered about the ailerons interacting somehow. (One a bit skewed at neutral, I had that issue with that once, that is why I asked)
Did you have any trim settings that seemed odd (even minor)?
Have you checked the thrust angles and AOI's?
Is the fuselage straight and true?
I have to admit that it sounds a bit strange that you have such a major difference, without finding any of the control surfaces out of wack, or a warped wing, twist or alike.
If you find an answer to the problem would you post what the cause was?