We're using this for some packages, where we're maintaining long-lived development branches, for example glibc. The latter one has usage examples, too.

Running it on GNU/Hurd

Nothing special to that, technically, only that our I/O system's (non-) performance will render this unbearably slow for anything but simple test cases. So don't try to run it on the GCC or glibc repositories. Talk to tschwinge about how he's using it on a GNU/Linux machine and push the resulting trees to GNU/Hurd systems.