Nice work. Maybe you could do some preprocessing of the XML data, so that you actually have a diff of the content and not the whole XML block.
I thought about it, but decided against pre-processing: The repo is meant to be an archive, and the XML spec can be looked up. If I were to introduce a new structure by pre-processing the files, I think that might be a plus for reading, but not for archiving. Whoever has a concrete use case (the "Digebu" website above looks great!), can write their own pre-processor for that use case.