No upgrade path?

In the release notes for the Drupal 6 version of this module it says there is no upgrade path. Does that mean images added with this version of the module may not work with future releases of the module? or does it mean images from the Drupal 5 version can't be upgraded to the Drupal 6 version? Just want to make sure as we are planning on creating thousands of different galleries in the near future, and want to make sure they will be safe.