Matt,
Not sure if you are still monitoring this or not, but wanted to thank you for your work and let you know that we are using this with Moodle 2.8.3. We have developed a SWF containing several lessons which we pass a lesson id to trigger the correct XML to be loaded with the SWF. Really handy feature of passing data.
So far so good, but one issue has come up. There does not appear to be a link to the Activity Progress Bar. Is this something that you have done any work on, or could?