We looked at the tools' ability to watch folders on the local Mac and upload files or keep them synchronised with remote directories on the server.
Captain FTP offers 'virtual folders' – applets that upload what's dropped onto them over to a designated location. It also offers watch folders for syncing data, but this needs extra software and failed to work.
Yummy FTP's FTP Watcher offers automatic uploading with local archiving. Cyberduck doesn't synchronise folders automatically, but it will do it on demand with download, upload and mirror options. Fetch only mirrors manually.
YUM! YUM!: Yummy FTP's Watcher feature offers automatic uploading with local archiving
Transmit's manual Synchronize options distinguish between mirroring and updating, and can download or upload as required. Droplets can also be made for quick uploads.
FileZilla offers directory comparison and synced browsing, but no syncing or mirroring.