John,
Provided you have a primary key mechanism that works for both buffered and unbuffered use you shouldn't have any problems. The buffered users won't see any updates made anywhere else and the others won't see the changes made by the buffered table until you commit the changes with TableUpdate().
You can pretty effectively test this yourself by opening two seperate VFP sessions on your machine and running your code from both of them.
>What happens when I have the same table in one part of the program buffered (5) and in a different part of the program appending to the table in un-buffered mode. One user is using the table in a form and it's buffered and the other user is using the table in a different form un-buffered and they attempt to write to the table at the same time?