I’ve got syncthing running on three solaris/omnios-server and as Andy stated the only issue that might cause some initial problems are file/directory permissions.
It is usually a good idea to run syncthing under a dedicated syncthing-user-account which is member of the user-group that will access the synced files. Due to the nature of the SMB-server all windows-user have to be mapped to a unix-user. Here it is important to understand that syncthing is running as local service with unix-like file permissions, while network users will access the directories via SMB. Thus managing access rights via ACLs is the only way to make sure that everything works as expected. Therefore one would connect to the unix-NAS as root and set the permissions via window’s permissions (properties/security).
Bottomline - syncthing on a unix-like OS runs rock-solid, but demands from the user more skills and knowledge about the OS than on windows!