up to now the nas distribution was offering btsync protocol to sync files between machines
since the btsync upgrade to 2.0 and the new limitations. there have been several discussions on openmediavault forums
some of us had already moved from btsync plugin to a direct install of syncthing expressed our experience with syncthing.
and since then a very new syncthing plugin for openmediavault have been released.
it allows to install the syncthing debian package and to configure the different instances (user, ports…)
then everything is done on the normal syncthing gui.
here is the g of github repository plugin for openmediavault :
here is one of the discussion about sync for openmediavault that went to syncthing integration 
http://forums.openmediavault.org/index.php/Thread/7885-BitTorrent-Sync-2-0/?postID=79896#post79896
the syncthing plugin for openmediavault is accessible by adding extra-ovm plugins repository and btsync plugin repository
maybe to add this on the installation instructions for each distribution