This is the only thing standing between me and purchasing EasyDiscuss. I think StackIdeas has great software, but I have a sizeable phpbb3 forum bridged in my Joomla site. Migrating to Kunena is a circus of circular references and downgrades and multiple installations and version-- it's insane. I honestly think that EasyDiscuss is the best solution, and that a good phpbb3 migrator would increase sales.
In my case, all my users are synced to Joomla already after having used the Alterbrains bridge. It's just the content (forums, topics, posts, attachments,etc) that needs to be migrated.