I recently used MozBackup to move everything from a Windows 7 laptop to a Windows 8.1 Surface computer for a family member and it worked well. The only thing was that once I restored the profile and then launched Thunderbird, some folders, e.g. Inbox, had weird duplicates, but I closed Thunderbird, then launched it again and everything went back to normal. [https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer#w_mozbackup MozBackup]