> I think I may have been using copy-of to start with, then 
> switched to value-of but by that time had altered the schema...

Copy-of will copy the text nodes rather than the typed value of the element.

The data model actually allows systems to reconstruct the text nodes from
the typed value, but I don't think it's a good idea and Saxon doesn't do it.

Michael Kay
http://www.saxonica.com/