Thanks for all your thoughts and suggestions Alan and Kevin, really helpful. I’ve added a couple more – feel free to add more when you think of them! I’m considering providing a link in the melodica description to another page called ‘review criteria’
Here’s the list so far:
moisture release valve design
quality of build
reed moisture tolerance
evenness of tone
number of keys (listed in description).
Alan – have you tried a Clavietta? The tone is really very similar to a chromatic harmonica…