Thanks for your reply!  I tried what you suggested, but unfortunately it
still copied all the paragraphs, including the paragraphs in the <div
class="mgronly"> tags.  This is the XSL file I ended up with . . .

The problem is that your div elements exist in the XHTML namespace.
Declare the namespace in your style sheet:

 <xsl:stylesheet
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:xhtml="http://www.w3.org/1999/xhtml"
   version="1.0">

HTH
J.Pietschmann