I've been following this thread as I'm having the same issue when I try to WinScp to my N900. The connection seems to get lost and times out. ssh rrot@localhost was working fine...
Checked my router status and both my Wnidows laptop and the N900 were there.
My solution, although very old school was to ping the router from my N900 and leave it. At that point WinScp connected just fine. Kill the ping, WinScp could not connect and complained. Very odd, but I got it working.
I made it NOT to load automatically, and create a script to start the service, wait for a keyboard input and then stop the server. So, when I want to connect, I have to go to the device, execute a program, go to the PC, connect and use it. When I'm done, I go to the n900 and press a key so it stops waiting for connections.
I had a hard time finding out how to create a ".desktop" file in /usr/share/applications/hildonm, but eventually got it working.
Venemo: I didn't know it is possible to use USB networking... it is better to save battery and no security concerns. I'll try it.