Offline Sync over slow link

We always had an issue with this working in XP, so I was curious about how it
works in Vista. Here is our issue. We have users that have their redirected
My Documents folder set to use offline on their laptops. They often travel
to other sites that have a slow WAN link back to their office. Whenever they
are connected- their computer sees their server and tries to open the files
directly on the server... which as I mentioned is a slow link. In XP there
was a setting that allowed you to tell it what the minimum bandwidth was for
working online- but it never seemed to work.
How does Vista handle this type of scenario? Is there a minimum a similar
bandwidth minimum? Can it work like Outlook cached mode does where it always
uses the local copy and just sychs the changes?