I recently custom installed a ZerO Glide on my 40 year old 12 string guitar and it really has done the business. There has been a marked improvement in volume and sustain tuning is much smoother and the intonation is spot on.
Pretty easy to install - sand it down to fit - pick the fret that matches the rest of your fretboard - couldn't be easier!
I bought this for a Washburn Oscar Schmidt OE-40B archtop guitar, on which the nut had broken when putting on new strings. I always wanted to try a zero-fret nut and was pleasantly surprised at how well it works. Perfect string height and tone.