Any android developers had any success changing the package name of your application (in the manifest) of an application already being distributed in the Market?
During
It's not that the saved preferences will be lost, it's just that Android will set it as a completely new and seperate program which cannot access the old application's preferences.
However, if you sign your applications with the same signature and and give them the same userId then they can share information and you could migrate the original application's information to the new one.