Here is a timeline of my experience with regard to experimenting with tuning harmonicas.
I first acquired a Melody Maker made by Lee Oskar, it has 5 and 9 draw raised a half step and blow 3 raised a whole step. I learned a few songs that made it attractive. But I didn't like the Tombo harps, so I set about having them retuned.
Then I decided to do the retuning myself. After a time, someone suggested another tuning, and I tried that--but I was running out of harmonicas to do it with. So I bought a device (from Bill Romel) to replace broken reeds (much like the F & R Farrell tool).
I had saved all my old broken harmonicas and so had some to use and learned to repair them.
I began offering my services to other harmonica players, and fixed their harps in exchange for some of the broken ones.
So now I have a variety of harmonicas to use when a new idea comes along.
I just repaired a high A diatonic harmonica (a Bushman) for Bill Barrett, and have decided to make one of my hybrid high diatonics in that key--see attached chart.
PS I use Special 20s by Hohner for the most part, and always welcome players who have a large collection of them which need repair and want to have me fix their harps in exchange for some of the broken ones.
PPS I fixed the chart, if you are going to do this mod, use the new one.
PPPS Attached also please find an audio sample of the harp, including my ruminations.