If you're better than the competition you should be profitable, and if your maths is better you're better than the competition.

I would pay for it. More importantly I would use it. Not everything has to have a price as long as everything has a value.

It's funny because I was trying to sing a melody into Musescore just the other day and had to apply a bit of Audacity and then remember theory from secondary school to make it work. My middle-age voice sounds different to a computer than to my ears. If you could make this easy and accurate you would do every amateur song-writer on this earth a huge favor, though maybe not every amateur listener :)