With the 2.75 setting, the results are closer to being correct but the issue is that now the benefit of smoothing isn't there so the results look jagged and sloppy in comparison to Sodipodi.
It does not make that much difference to me at all. I draw smooth curve and I get smooth curve, with just a barely noticeable increase in bumpiness at 2 than at 10.
OK, I guess this is really a useless argument because the results depend too much on your manner of drawing and the tool (mouse/pen) you use. For you, Inkscape is unnatural; for me, Sodi is absolutely unusable. Personally, I do not feel any pressing need for improving the Inkscape freehand tool now, except for lowering the default tolerance and fixing the ghost spikes, and I would certainly not welcome changing it towards Sodi's lagginess and oversmoothness. So if you make any changes to this code, I want to ask you to leave the current Inkscape behavior available because that is what I prefer.