Using XSLT 2, this combination:

  <xsl:strip-space elements = "*" />
  <xsl:template match="element()|attribute()">... skip selected *|@* ... />
  <xsl:template match="text()|@_ix">
    <xsl:copy-of select="."/>
  </xsl:template>
  <xsl:template match="comment()">
    <xsl:copy-of select="."/><xsl:text>
</xsl:text>
  </xsl:template>

is the best I could do to preserve the original comment and element
layout, shown with beginning of input and output XML, below. Can this
be improved? Losing empty lines is tolerable, losing line breaks is
not so great.

Thanks
Wolfgang

<xsl:template match="/comment()" priority="2">
   <xsl:copy-of select="."/><xsl:text>&#10;</xsl:text>
<xsl:text>

<xsl:template match="comment()">
   <xsl:copy-of select="."/>
<xsl:text>

<xsl:template match="/" priority="2">
  <xsl:text>&#10;</xsl:text>
  <xsl:apply-templates/>
<xsl:text>

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