Hi dpower,
When I started working on this, I had an ISY-26 and there was no rest interface. It actually took me a while to convince the UD guys to give me the web services information back then. So since it works, I never went back and tried to rewrite it. For the XML parsing, there were some issues with either the formatting that gets sent by the ISY, or trying to get minidom working in the limited python set that comes with Eventghost (or that did at the time of coding). Sadly it's been so long I can't remember. =)
But I've had this thing in operation for a few years now, and it's been stable. I use an eventghost timer against the ISY heartbeat signal to reconnect to it if it drops. Honestly, the biggest problem is that if you go into the ISY admin interface, it still (stupidly, after all this time) resets the log level to 0! This blinds the plugin to a lot of commands until I notice it and resend the command to set it back to 1.
If you make any changes or want to share what you've done with the REST stuff, I'd love to see it.
~K