mobious, I could be mistaken but I don't think you can as easily manage clients like this anymore by just copying a GRC.DAT file as version 10 now uses PKI Certificates I think to ensure that clients don't move accidentally between sites as they did in the past for mobile travelers.
This also helps to ensure integrity between servers and clients.

I would do some more testing and/or speak with Symantec Technical Support to ensure this method will work correctly for you.