Just discovered another problem.

If zipship is unable to find a rate against the postcode then it displays 'Sorry. Delivery is not available to selected address.' and cannot be selected, and pressing the continue button basically doesn't work.

with checkout_one it does this properly in the shipping selection boxy, however it displays an old rate (plucked from where?) in the summary at the bottom of the page. And if the user pressess continue a couple of times it will let them through.