Good review, especially of django. However, one tiny gripe: it's actually really easy to use an arbitrary templating system with django. Since HttpResponse objects just take strings, you don't have to use render_to_response(..), you could easily generate your html string from mako and pass that to a hand created HttpResponse (or write your own render_to_response).

I also don't think it would be very difficult to amend the url dispatch either.