So I just created a mobile service on 10.1 Server and went to connect in 10.0.0.0 Mobile Project Center and while it initially says it connects it then has a red exclamation mark with the error message "Error: Unknown".
I've now tried it with a number of map services with no luck. These map services all work with Mobile Project Center 10.1.1.
Some of these map services have attachments but most don't.
So can I say conclusively no you can't connect 10.0.0.0 Mobile to 10.1?