Sufficient yes, but still a pain. The problem is that you can't do
something like:

<xsl:variable name="foo">
   <xsl:choose>
     <xsl:when test="function-available(...)">
        ...

   </xsl:choose>
</xsl:variable>

It's been a while since I bothered with this, but I think the pattern
goes something like:

<xsl:variable name="foo-rtf">
....
</

<xsl:variable name="foo">
 <xsl:choose>
   <xsl:when test="function-available(...)">
....

I guess its good that people persist with client side XSLT (as one day
it might be worthwhile), but I reckon its just a hangover from the
original intentions of XML.

cheers
andrew