I currently have 7.x-1.x-dev and I am running Drupal 7.14. On my module update page there is an update for Rotating Banner to 7.x-2.x-dev. But there is a message which I have copied below. I don't see anything in the release note that helps me understand if there would be an issue with backward compatibility for me.

"This update is a major version update which means that it may not be backwards compatible with your currently running version. It is recommended that you read the release notes and proceed at your own risk."