David,
I appreciate the addition to the conversation. I had seen that mentioned when I was doing searches online. So far it looks like the "Move to SharePoint" method will work well. Because users store a local copy of the linked lists on their PC, they can still enter data offline, and then the software does a great job of syncronizing later.
Now, anything that is nor forced to be unique may still present an issue with offline entry if for some reason two users added the same record offline. But, I think that would happen with any synchronization approach, and for that matter, with fields not forced to be unique, I suppose could still happen if all data was entered while both users were online.