The internal reroute option doesn't work when posting form data on the splitform demo.
I setup a reroute for /myform -> /demos/splitform
The initial page shows the url as "/myform", but when you click next, it will show the url as "/demos/splitform" again.
I verified demos/contact and demos/tablemanager don't work either but this probably affects all internal reroutes for pages that have a form.
Also, I looked at the $_page object and it doesn't appear to store the original url which would be helpful to have.