...become a bench mark for good reading in younger children?
Yes, in order to decode Harry Potter you do have to be a very competent reader. But the themes and ideas in the books - particularly the later ones - are entirely inappropriate and largely incomprehensible for KS1 children, and anyway there is a world of better written, age appropriate for good readers of this age to get their teeth into without adding to grip Rowling has on childrens' fiction.