Regular nut vs. this one = draw. Yes, strings touches the fretboard in those grooves, but they are not putting any significant pressure on the wood. When I tune, the string glides without leaving string too loose or tight on headstock side. My tuners are not locking ones, but they do the job (at least at home).
I will make a video as soon as I have time. :)
RE: Guitar zero fret - The best fret (ever)!