Trouble With Sitemap And Roles In ASP2

Has anyone else had any trouble setting up a sitemap view to be
filtered by roles?

We've put a cust role provider in place, and we can verify that it's
only being called once for each connection, and is returning the
correct roles, but...

When we specify a role on the top sitemapnode that role seems to add to
the roles on lower level nodes, so we end up needing to put roles="*"
on the top node, but then regardless of which role we put against the
subnodes they're all visible - seemingly inheriting this from the top
one. Code: