Another option just occurred to me:
Transmit, Interarchy, or ExpanDrive (http://www.expandrive.com/) and Hazel 3.
Hazel 3 has a 'sync' option. It only works on folders mounted on thatMac, but if you mounted the server as a 'local' folder, I think itwould work.
(I'm using it to sync my Byword iCloud folder to Dropbox.)