> Currently, they seem to favor xml-rs which only implements a subset of XML.

What in particular do you find objectionable about this implementation? It's only claiming to be an XML parser, it isn't claiming to validate against a DTD or Schema.

The XML standard is very complex and broad, I would be surprised if anyone has implemented it in it's entirety beyond a company like Microsoft or Oracle. Even then I would question it.

At the end of the day, much of XML is hard if not impossible to use or maintain. A lot of it was defined without much thought given to practicality and for most developers they will never had to deal with a lot of it's eccentricities.