Hi Rich,
Out of curiosity, what happens if you use the Offline version instead of the Deployment version export. It's been pointed out that there were some changes made in that for similar reasons (restrictions on loading xml files locally in a browser).. Despite being saying "offline" you might find that it actually works in your case and if it did, even somewhat, and you were able to feedback what does/doesn't work then we may be able to do something quicker rather than later to fix this issue... I'm sure Canvas wont be the only ones doing this both now or in the future...
Regards,
John