Never done one but I have played an old guitar with one on.  The biggest issue for me is that the zero fret wears and gets a groove where you get a pinging sound especially bending nearer the nut. You could put a stainless steel fret in as the zero fret to ensure that doesn’t happen. 

Use a larger fret for the zero than the rest so maybe a jumbo and mediums for the rest. 

For me it takes away flexibility as with a nut you can higher and lower the height as you feel fit (thinking set ups for slide).

It’s always worth a go as an experiment for yourself. You never know it might be just how you like the guitar set up.

The Maccaferri necks that I have made all have zero frets. I would definitely recommend a slightly higher fret (one size up) for the zero but also remove most or all of the tang and either glue it in place or just leave it a snug fit, as they are usually so close to the end of the fret board that, if you just bang it in like all the others, little bits of fret board tend to go flying all over the workshop and they are a nightmare to jigsaw back together again (I imagine!!) If you make it a snug fit, and therefore mainly held in place by the string tension, then it is pretty simple to replace it if it develops grooves.

I would say it's a bad idea because the zero fret is under string pressure all the time and is bound to wear faster than the other frets. Ive repaired lots of guitars with zero frets and also think that a higher fret is needed. Did think about replacing with a nut but the edge of the slot is slightly in front of where the fret crown would be so not sure if it would affect the intonation.

A good pointer is that top end guitars don't use them apart them the Gypsy Jazz style where they seem to be acceptable.

I would say it's a bad idea

I'm coming round to that way of thinking too @rocknroller912.

I need to build some necks, and I was considering all the different options.  But I think I'll stick to a more standard design.  No need to over-complicate things!

the zero fret does not need to be bigger than the other frets,

if you think about it, if a bigger fret was needed then the first fret would need to be bigger than the second fret, the second fret would need to be bigger than the third and so on, 

i have just finished my second build which is a les paul copy, 12 string semi hollow, with a zero fret, all the same size

the zero fret does not need to be bigger than the other frets,

I have my guitar necks with as little relief as possible and the action as low as possible so it just gives a little tolerance being slightly bigger.

The nut slot on non zero is usually slightly higher than the fret heights on all my builds and most of my bought guitars. I’m sure you are correct that they can be the same height but it’s just what Ive found on mine and I know there is a lot of debate in this regard on other guitar related forums. Trying both is part of the fun.