John,

So far, those who have had this done have not had
difficulty in obtaining a field approval for the change.

Very interesting, thanks! Our EASA is not that flexible, I'm afraid.

Regardless of how the autopilot is determining the course, the
pilot is required to be displaying the ILS localizer and GS on the CDI or
HSI, and must use the CDI or HSI to determine if corrections need to be made
or not.

Agree. Would you agree that a properly set-up S-TEC should be able to follow a
localizer without too much weaving about?

--
Thomas Borchert (EDDH)