Did not work all that well. The big problem came when I wanted to remove it. The uninstaller leaves the Spanning Sync icon in the system preferences. When you click on it, you get Preferences Error: "You cannot open Spanning Sync preferences because it doesn't work on an Intel-based Mac". Searching on Spanning finds no files to delete.

And the final straw, there is no email link to ask questions at the site. Just useless FAQs.