So I'm trying to visualize this, and failing. I don't suppose you'd toss up an example? I'm curious to see how you'd address a mix of attribute value pairs and element names and content. It's been at least 15 years since I messed with lisp.
I deal with XML every day, and agree with the verbosity and ugliness comment. The only way i can make it palatable is lots of indenting, and syntax highlighting, and even then it's pretty rough some times. I like it's flexibility and ubiquitousness though. I don't hate it nearly as much as I dislike the SQL language.