yes, I am really interesting in your example. Last summer, I was researching in this field because HSM is the evolution for state machines. I think that HSM is more versatile than subsumption architecture so if you have some example, I would like to test. I have other implementation but you are the first leJOS user who are interested in this area.
I would like to test your idea.
I send you other alternatives:
Take a look the package about HSM for ROS: