Your right.

Though I think the first thing to establish is if it IS possible for different sites to change the same records.

If it is then that would indicate attempting ANY form of remote synchronization was a waste of time (as you said above which was why I wrote it).

Once you have established that there isn't any overlap the Transaction file would be a perfect way to keep everything up to date on the central server.

It would also cut down on the throughput if only the changes were sent in the transaction log although you would have to make sure there is an ability to either :

1. Re-request a transaction log if it went missing
2. Ability to generate a FULL dump should things go wrong