Just clutching at straws here, but if your XF is on the same server as your vB, using the same DB server, and you don't have a charset set specifically in config.php for vB, don't specify it for the import. Assuming that the 'latin1' qualifier is unnecessary, it might be worth starting again without it to see if it makes a difference. Failing that, drop me a support ticket with SSH details and I'll try to figure out what's going on.