First blues player I heard expressing a deep interest in using diatonic in reggae music was Paul Messinger way back in the 90's. I was pleasantly surprised to hear him actually do it quite nicely in his recording projects "America" and "Climbing Jacob's Ladder".
Actually, the "America" project is quite stunning on many levels - not just the harmonica playing, but the songwriting, production and execution as well! ---------- The Iceman