I've been using xBrowserSync for over 2 years to sync 4 devices without issue. I do occasionally export my bookmarks for backup, but haven't had to use it. I switched after losing years of bookmarks to a Firefox sync issue. One of the best things about xBrowserSync (for me) turned out to be its workflow. I can't imagine going back to bookmarking in nested folders. Using tags with search is just so much better.