I need to backup many sites over slow, high latency satellite links. We are talking pings of 650ms to each site. I can get a dump of the initial data by sending out USB disk to site and restoring it at central office. From then on I intend to use rsync or DFS-R for byte-level incremental copies across the link. All the machines are Windows 2003 SP2 R2. I have read that rsync can hang on large files and is still a bit flakey for Windows?

Alternatively should I use DFS-R which also does byte-level copies? 

I have tried DFS-R in the past and was not impressed by the lack of logging, it was very hard to find out what was actually going on. That's why I'm interested in rsync. Has anyone any real world experience of both methods?