Re: output the result of the transformation twice, in

Indeed it is ... but what if already you had written a template for the root node? Using <xsl:apply-templates/> as you have above would push the children of the root node and your previously-written template for the root node never would be triggered.

Graydon's approach saves the time for executing the transformation twice, but with the penalty of internal storage, so youB would have to factor that in to weighing your alternatives.