The other way 'round would work ie v11d media server talking to v10d RemoteAgents, but it would be a violation of the Symantec Licensing Policy to run it this way in production. The SCL specifically says "for the purpose of rolling upgrades"
I don't think you will ever get a down-level media server to connect to a current RemoteAgent
You also won't able to install v10d with v11d serials
Used to be (Back in the Veritas v7 and v8 days) that you could call Support, give them the current serials, they would EMail you back one level old serials, but I just don't see Symantec doing that.