I was hoping to sync bookmarks across several machines, some with Firefox and some with Chrome or Vivaldi. This feature doesn't work - trying to download or merge bookmarks to Chrome or Vivaldi results in either a crash or hung app, usually after it has deleted all your current bookmarks but before successfully downloading most/any of the bookmarks stored on the server.

It also slows down your browser startup noticeably, and is set to auto-backup your bookmarks to your local machine, but doesn't let you modify the backup location. I went to their forum to see if any suggestions were available, but discovered numerous threads with the same problems I'm having, but no solutions.

Might be OK if you are using Firefox exclusively - but if you're using Firefox exclusively, you can use Firefox's built-in sync, which doesn't slow down your browser and doesn't fill up your SSD with backups.