Importing to Evolution in Karmic

I'm planning to do a clean install of Karmic 32 bit and have been planning this using an installation in Sun Virtual Box. I want to import my mail and settings from my existing installation (Jaunty 64 bit). I used the File > Backup Settings option to create a backup and tested this by using File > Restore Settings (still in Jaunty), which worked fine.
When I tried to do the same, using the same backup, in my Karmic install, I got an error: Invalid Evolution Backup file.
I thought this might have been caused by a change to the backup formats so I tried File > Backup Settings from my Karmic install and then File > Restore Settings but still get the same error.
Is there either a fix for this apparent problem or another method of exporting mail etc from a Jaunty Evolution installation to a Karmic Evolution installation?