[Brent Hutto]

The width of the neck has nothing to do with the ability of the strings to vibrate. It has to do with the ability of the player to utilize the full range of classical technique. Not everyone needs a 52mm width at the nut or even 50mm, it depends on what techniques you are using and how precisely you can manipulate your left hand. I doubt there are many classical guitarists who could get by with less then 48mm or so but I'm sure there are some.

Then again, if you're going to play simpler stuff (non-classical) without much in the way of vibrato or extremely tricky fingerings a narrower neck may work just fine. But in any case, nylon strings are a bit "fatter" than steel ones and take up more room so you're likely to need at least a little wider neck than on your steel-string guitars.