Hi, Johan,
Are you familiar with alt+pencil tool sketching? http://wiki.inkscape.org/wiki/index.php/Release_notes/0.47#Pencil_sketch_mod... The idea was to be able to roughly sketch a shape, then release the alt button and have Inkscape "trace" the sketch for a smooth shape. Perhaps your work could be the key in doing this :)
I haven't seen it before, but it makes sense--using oversketching to refine a curve is natural for artists. I think it should be possible to improve the result quality using my algorithm, but it's not completely obvious what the right interaction is. I don't think Alt+pencil currently gets it quite right (e.g., oversketching starting from the middle of a curve moves the beginning instead of editing just the part that's oversketched), but there's a lot of potential. These guys: http://www.dgp.toronto.edu/~shbae/ilovesketch.htm have an interesting take--watch their sketching from the first minute of the video.
I haven't got the time right now to look at your demo, but it sounds very interesting!
Like Aaron wrote, it may be interesting for lib2geom too. Be sure to send a mail to us on the lib2geom maillist :P
At this point it sounds like there's definitely enough interest for me to proceed. I think I'll start a discussion with the lib2geom folks when I have some code to show :)
Thanks,
-Ilya