Seemed reasonable to me.

Of course, maybe you oughtn't try to convinve people too hard of this... instead take their pennies. ;)

Oh, a bit off topic, but on the subject of coherence/dutch book/vulnurability arguments, I like them because:

1. Depending on formulation, they'll give you epistemic probability and decision theory all at once.

2. Has a "mathematical karma" flavor. ie "no, you're not good or evil or anything for listening or ignoring this. Simply that there're natural mathematical consequences if you don't organize your decisions and beliefs in terms of these principles." Just a bit of a different flavor than other types of math I've seen. And I like saying "mathematical karma." :)

3. The arguments of these sorts that I've seen don't seem to demand ever much more than linear algeabra. Cox's theorem involes somewhat tougher math and the derivations are a bit longer. It's useful to know that it's there, but coherence arguments seem to be mathematically, well, "cleaner" and also more intuitive, at least to me.