You'd (hopefully) pick the notation that allows the performer to give the best performance.

One reason for 3/2 would be that the song is slow, and seeing half notes helps the performer feel the tempo correctly. This is where I've seen it used.

Another reason might be for readability, if you decided that is was more playable without the performer having to decode a whole bunch of 64th notes.


-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?