Well, SFFS has now uploaded about 30MB of the 6GB I pointed it at and the ETA to completion is over 4 days.
This would seem to imply that my uplink is only running at about half the speed I would have expected, if I've got my sums right.
I should have done those sums before, I suppose, but for the amounts of data involved if you are an active photographer I think remote storage using an ADSL uplink is pushing the boundaries. As I mentioned, that 6GB would have taken 4 days and that is only a fraction of the photographs that many of us have on our computers. Just considering an active day when one might shoot, say, 100 photographs. At 5MB each that runs to half a gigabyte of data. OK, a lot of those may not be "keepers" but, on the other hand, start some post-processing and aim to back up the intermediates and that half a gigabyte can easily be reached again. On the basis of what I saw this morning that amount of data would take 8 hours to upload. I'll stick to my Network Attached Storage backed up by a couple of USB hard disks kept in a fire safe. Much quicker if not quite so bulletproof.
In fairness "Super Flexible File Synchronizer" would be great for backing up smaller amount of data on Amazon S3 and the speed issue isn't any fault of the program. I'm just about to uninstall it, though.