I got burned by AeroFS recently. Uninstalled AeroFS and then wiped one computer; when I woke another one up, all the data I had synced with the first computer started getting deleted, as indicated by many Growl notifications.

I could not stop the action and was only able to recover bits and pieces of data from deleted blocks. On OSX, one might think that deleted actions would move the file to the trash but, nope, straight up deleted. These two unexpected behaviors have convinced me drop AeroFS and stop telling others about it.