scalloped frets originate from lutes built in the 16th century. back then they had no such thing as metal frets so they simply carved away the wood between "imaginary" frets or sometimes frets that where made of animal tendons wrapped around the neck in order to give the feel of high frets.

I think one of the first persons who tried that on the electric guitar was Malmsteen (he worked at a luthier back then and saw one of those scalloped lutes).

I tried it too on an old crappy guitar and it was quite cool. you need less finger movement and you can play more relaxed for you dont have to push the string that hard against the fret. with scalloped necks it does not realy matter WHERE between the frets you put your finger - you will always have a clear tone without fret noise.

But u have to get used to it big time for its an entirely different feel compared to normal necks.

I was thinking of having a guitar built for myself with scalloped frets from the 15th fret upwards, for it makes the fingering much easier and accurate on the smaller fret spaces.

The disadvantage is, than when u use too much force when fretting a note it gets easily out of tune for it is as if you where making a bend.