conditional instruction vs. conditional expression

What are the advantages and disadvantages of passing a string parameter
via a conditional instruction (XPath 1.0):

    <xsl:with-param name="content">
      <xsl:if test="mb3e:org_list/mb3e:org_code[@type='APPR' and
                                                text()='ANSI']">
        <xsl:text>*</xsl:text>
      </xsl:if>
    </xsl:with-param>

vs. via a conditional expression (XPath 2.0):

    <xsl:with-param name="content"
         select="if (mb3e:org_list/mb3e:org_code[@type='APPR' and
                                                 text()='ANSI'])
                 then '*'
                 else ''"/>

Thanks,
-- 
Kevin Rodgers