Hi Dave
Do you have a webserver running on your local machine/laptop? Makes these sort of problems much easier to resolve. I’m running on Mac and use MAMP PRO which takes a bit of setting up, but once you have, it really helps to test stuff out rather than updating a live site. When you’re happy backup with “Backup WordPress” update the database and files on your live site and you’re done.
I know this doesn’t answer your question, but I thought I’d mention it anyway. I just bought Dante as well and it installed fine on WP 3.7.1. The only way I could install the demo data was to do it locally and then upload the backup.
Good Luck Basil