Xeddy follows your formatting habits as closely as possible. Whenever you directly change the XML code (it is visible at all times during editing), Xeddy immediately updates the structure view.
Moreover, Xeddy has a pluggable interface for XML parsers. Currently Xeddy uses Apache's Xerces implementation, but as soon as Sun Microsystems finish at least the SAX part of their parser, Xeddy will be able immediately to use it. So will you.