You really brought it!! I loved it :).
To be honest, I didn’t even catch the jump from 440-450 on my first listen. But my ear never got used to 430 for more than a note or two. The jump to 450 from 430 was crazy sounding, but my ear adjusted almost immediately!
I’d LOVE this kind of feature on a melodica.
In fact, I’ve designed a melodica Eurorack synth controller that I hope to some day build. One feature that I wanted was three analog push-buttons (like a trumpet) on the top. The outside buttons would work as pitch bend controllers, one being the inverted CV of the other (for pitch-up and pitch-down). The middle would be a modulation amount controller or something like that. Of course this would have no actual sound coming out of it…
HOWEVER, I wonder if it’s not possible to create a mechanical obstruction within the air chamber that could be added/removed via a couple of buttons in conjunction with a release button (i.e. if button A is depressed then the airflow would be limited to a smaller space thus raising the air pressure and lowering the pitch and if button B is depressed then an extra chamber is opened up increasing the airflow and lowering the air pressure thus raising the pitch). If the release button is pressed while button A or B is depressed then the previously depressed button will be released thus returning the melodica to its standard tuning.
The thing is, though, the second you open up a melodica you realize how little space there is to tinker with!
I’d love to see someone build a solution for this :).