Ubuntu One should support syncing file changes, instead of re-uploading the whole changed file (example use case: syncing Truecrypt container)

[Esokrates]

According to my experience all information I have found so far, Ubuntu One, unlike Dropbox, does not support syncing file chages, but re-uploades the whole file that has been changed instead, making it impossible to sync large TrueCrypt containers, as with every change (even if only a few bytes are changed) the whole container would have to be re-uploaded.
It should be possible to only sync file changes like in Dropbox, where only the changed blocks are uploaded in case of a change to the Truecrypt container.
I know Ubuntu One is not a backup solution by design, but it would provide many benefits it this feature was implemented and I am also aware that file based encryption is possible, but I would really like to see that feature.