I'm using jacknorris' USB hotplug patch on top of a stock 4.2.1 ROM, and the 4.2.1 kernel in his thread.
BTW - what color does your DragonFly light up when plugged in? Mine is always pink unless USB Audio Recorder PRO overrides it.
I did see an ALSA error message in the kernel log. The kernel is definitely detecting the DragonFly but still no sound comes out. I'm no stranger to the Android framework and kernel so if it's an easy fix I might look into it myself.
When I was testing the DragonFly, it was lighting up pink as well. It would be great if you could hack a fix for the DragonFly. The Nexus 7 and DragonFly would make a great combo.
I think there is a bug in the hot plug implementation. I can reliably crash the setup. Luckily, jacknorris knows about it.