Nested table containing XMLTYPE

I am new to using XML in an Oracle table.  I know you can specify a column in a table as a CLOB or as XMLTYPE (stored as binary) but also in XML DB which would be 'strucured' and suit our purposes better as we want to query many fields in the XML.  We have an existing table containing 'ordinary' datatypes VARCHAR2 etc, 2 columns of which will contain XML.  Traditionally we have defined these as CLOBs but querying isn't optimal.  We then defined these as XMLTYPE (stored as binary) but have to put xmltable (... etc clause in the SELECT