I have a suggestion, though I don't know much about improvising and haven't listened to it all the way through. I was wondering about maybe using some more rests, perhaps even with fermatas? There is so much good material here, but it all sort of runs into each other. I was thinking of something similar to the opening of the Pathetique, though not in that much of an excess. Beethoven really catches and grips our attention here because the silences add drama to the music. Also, in Bartok, he uses rests and pauses and fermatas, to really say, "Now listen to what I'm going to do next!" Often changes in mood are really "announced" this way, though, they are often a surprise as well. I suppose it really depends on one's style of improve, too, but it think it would cause it to sound more like a written "piece" rather than, well, improv! Unless, of course, that's the sound you're going for.
Also, this is trully just a personal preference, but I think if you put even more rhythmic motives, and/or some slower chordal sections, it would sound less "noodley" for a lack of a better word. Right now, it sort of reminds me of Ravel, in that, it runs all over the piano, for the most part, which is hard for an audience to stay attentive to for long periods of time. But this you can take or leave, because that's just my personal musical tastes.
But it's definately awesome, Derek!