[AndyL]

Switching to the up = sharps, down = flats model means you can always change what you've got by transposing up 1, then down 1 to switch to flats or down 1 and up 1 to switch to sharps. So this might be the simplest and avoid a lot of confusion.

If you do this, it would be nice to have up and down buttons you can keep tapping and be able to see what is happening as you do. You can then keep tapping until you get what you want.

Andy