"Zero frets are in constant contact with the string, when crowned properly the string intonates well and sounds fine but over time the "lead off" shifts forward as the zero fret wears down and the intonation shifts across the board. I can't actually hear the difference (which is why I don't deal with earvana or feiten systems) but what I CAN hear is fret buzz when the zero fret begins to wear. Changing out a worn nut (which takes WAAAY longer to wear down) is a cakewalk compared to removing a zero fret, sourcing and installing a replacement and adjusting it to match pre-existing fretwear."
I came late to this discussion, so this might be an old point.
However, I have some disagreements with the above.
1: The intonation point 'shifting' forward is, by his own admission, too subtle to hear. Furthermore, the tiny amount
it moves might even help you, since many of the intonation-correction approaches involve moving the nut slot
slightly towards the first fret.
I compensate the location of my zero frets, since I can
measure the difference with a good tuner. Intonation is
one of the few objectively quantifiable qualities of an instrument.
It seems a bit strange to dismiss something because you
"can't hear" it, if it is measurable in more absolute terms.
2: Next - a nut takes "WAAAY longer to wear down"?
I don't think so. Fretwire is harder than many (maybe most?)
nut materials I've ever used. I just don't see what the big
issue is here - yes, the fret is in constant contact with the
string. However, the contact is relatively static - the contact
point doesn't get all that much movement (read: abrasive action
from the string winds).
Zero frets are a great idea, that got a bad rep due to cheap
guitars in the '60s. They work really well, sound good,
last a long time, are much easier to set up properly, are more
tolerant of string gauge changes, and are generally really excellent.
If you don't believe me, just ask MTD, Elrick, or any of the
other fine builders that are using them very happily.
I'll get off my soapbox now.
Cheers,
Martin