Almost all of my guitars have the tuning post arranged either in a straight line like this:
Or fanned out like this:
This design requires the strings to deviate dramatically from a straight line after they pass through the nut slots - particularly the two middle strings.
Many electric guitars use a headstock design similar to this:
Which have the advantage of allowing the strings to continue past the nut to the tuning posts while staying in a straight line.
Some acoustic guitars also have a reverse taper to the headstock (Christmas Tree shape) where the tuning pegs converge instead of fan out - like these:
which minimize the angle that the strings deviate from a straight line.
It seems to me that torquing the string to the left or right as opposed to allowing it to remain parallel to (in line with) the nut slot - would put lateral pressure on the side of the string and have an effect on the way it vibrates. I have noticed that if I use a string gauge that is much larger than the nut slot is cut for, that it tends to dampen the string - perhaps because it is pinched in the slot and can't vibrate freely.
So my questions are:
Will this sideways torquing of the string negatively impact the strings resonance or sustain (when played unfretted) by decreasing its ability to vibrate freely?
And if there is an advantage to minimizing the deflection of the string - why don't more guitar makers use a headstock design that allows the tuning pegs to be more in line with their corresponding nut slots?