OK, I just performed the experiment to determine what Melodyne can do regarding turning a vocal track into believable MIDI.

I recorded a short vocal melody in RB,
Exported it as WAV
opened it in Melodyne
tweaked it a little, (but it might not have been necessary)
saved it as MIDI
reopened it in RB
examined it in the piano roll to see if Melodyne captured the velocity changes. (it DID!) see graphic below:

As you can see the lower pane shows variation on the velocity. I applied a good soft synth that is capable of using the velocity difference to take advantage of different sounds at different velocities. As expected, the synth sounded different based on the velocity.

With a little practice, once you know how to obtain the velocity breakpoints your soft synth requires, you could really blow it out of the water with just your voice as MIDI controller!!

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velocity.jpg (175.55 KB, 104 downloads)
https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0