Definitely a good idea. I have the Members plugin installed on one of my sites. The changeover was smooth, and afaik no functionaility has been removed, but as my process for installing plugins is to first review the plugin's support history, reviews and get a general feel for the author through their responses and plugin library, this could all change dramatically in the event of a plugin changing hands. A notification would be ideal so I could review the history of the new author/owner before updating.