You mentioned Melodyne...I wonder if the pitch module in my Nectar plugin would work for this? That is something else I guess I should try.
I guess it would constitute due diligence to look at that... but Melodyne has several different features... and the pitch correction feature is separate from the audio to midi feature. Whether Nectar includes that too would be something to look at.
Regarding whether or not I have used the audio to MIDI converter in RB: I've experimented with it, but never used it in a project. I'm not sure if it's polyphonic.. it might just be able to convert single notes at a time.
Depending on which version of Melodyne you get, some are able to convert chords to midi, some aren't