Actually there are a few benefits that HD gives besides just privacy. There are a few features we haven't been able to add until we got this HD thing implemented. But we're getting there!
I'll be impressed if you get it to work! I would have thought that the architecture of Mycelium, where the central server keeps track of your "savings", made this impossible. How could the server know which addresses to track? It might be possible, just difficult, but that's a challenge for you guys..!