So in XML::Parser in Stream and Subs mode they're definitely not per-element, so you'd need a gigantic switch-or-equivalent statement in your one-and-only StartTag routine to identify and instantiate the particular class you're after, plus it maintains no context (such as a parse stack) for you to tie into (I understand that this is a major reason for writing most of the other Perl XML parsers in fact, even though you can kind-of work around the problem using closures), plus it's not at all OO.
XML::Twig also doesn't seem to have a good solution, in that it instantiates all elements in the same class — a user-selected class to be sure, but always the same one.
I've discovered a name for what I'm after: XML Data Binding. Here's an article on the subject. It's Java-centric though, and doesn't offer any Perl answers...
