The back-up should work completely from your PC via web interface and without SambaShare. Just download the file from the old Max2Play and upload it via web interface to the new one. I tested this here without a problem, it even migrated the Spotify login from Spotty.
You should get these infos after clicking restore (having selected your file from Explorer or other file manager on PC):
Trying to Restore Squeezebox Server Settings…
File move successful
Settings successfully restored! Please restart Squeezebox Server now.