Right now we are looking to support sync on Win32, stayed tuned to our blog for more announcements. Once this lands we could replace SignalR depending on the client-side technology you are looking to support. RMP is most effective for mobile apps, like Android and iOS, however, we do have a node.js binding that could be used to synchronize servers with a central Realm Object Server (ROS). What kind of clients are you looking to support?
The sync protocol uses Websockets so it is bidirectional and will immediately update the remote database when changes are made locally.