I got simple octave rounding working in Pythagoras last night. Between this being still unfretted and me being sloppy, the playing is a little out of tune. But considering the speed and octave range, it isn't awfully out of tune.
Maybe the microtonal slider will snap to 12tet at lowest setting, to the harmonic series approximation to 53tet somewhere in the middle (for very tight chords with respect to the drone), and fully fretless all the way over to the right.
With octave rounding, you don't need a lot of octave range to really run up and down the board...just room to reposition from the left or the right. It's not quite what I want, but it's a start.