This is really interesting, but I'd like to see some level 1/level 3 comparisons for the app as a whole. What is being gained by the user progressing? A more minimal, less cluttered interface? You would think the beginner is the one that needs that interface, not the expert. In addition, how do you bridge the gap from "icon on a button" to "using keyboard shortcuts", which is where your expert users are really going to be spending their time.<p>That being said, I think the adaptive interface concept is really intriguing, and if executed right could be really useful