I'll look further into using Windows Live Mesh, although is does seem like the old Briefcase from Win98.
Noting your comment excluding the cloud, I am only really interested in direct access (or VPN when away) without a third party or internet needed.
The key features I want are:
i) centralised storage for backup and multiple user access,
ii) offline replication of, and access to, selected files during trips away from the network, and
iii) continuity of access to open files during intermittent wireless network dropouts, without the network version overwriting the open offline file on reconnection.
"Offline Files" in Win 7 seems excellent (when on a domain), given these new features (background sync and transparent caching) that appear to be designed exactly for this purpose. I just can't figure out a way to do it without having to set up a full server.