Max Andersen wrote:
You can go back and forth between installations by the Installation history in eclipse.
It works only if eclipse have access to plug-in with version saved in history and can install it from update site. It is not working for JBT because we have only most recent version available through update site. It means update M1->M2 works, but to be able to restore M1 you need update site for it to be available in eclipse.