My conclusion is that when you add it all up, the net evidence doesn't justify a position very far from 0.5, and to take a position like 0.01 or 0.99 is really an expression of personal bias.

Well thats an interesting conclusion and maybe someone has written something somewhere demonstrating that the right posterior probability given our science is around 0.5. But you can hardly expect your reader to have any idea where that number is coming from. 0.5 sounds much too high to me though what I know I basically know from general scientific knowledge and having done a science report on Mars in the 4th grade.

I agree that 99.99 or 00.01 seem much too extreme for estimations given our evidence- but they'd function perfectly fine as priors, was my point.