Why does your disagreement point lie outside the set of possible outcomes? If both are derived from the same game, one should lie within the other.

To emphasis it's essential arbitrariness :-)

Otherwise, great post and great diagrams. Thanks. Will your next post give a proof of your conjecture from Mar 15?

Thanks! I don't know my conjecture form Mar 15, but the result I have is a new one. Essentially it deals with how to maximise utility when you're unsure about what games you'll be playing. I'm still checking it, and ageing it.