Me. I play mostly blues harps and I routinely tune all of them to the Paddy Richter tuning (raising the 3-blow reed by a whole tone). I also retune my harmonicas to equal temperament fine-tuning (some already come that way but many do not, and I particularly dislike, in the latter, the 5-blow and 8-blow sounding slightly flat in melody playing). I should add that I play just traditional music, mostly Irish, Scottish and Northumbrian, in that order of frequency. I also gap the reeds of my harps to ensure I get the response I want (I don't do overblows and I find the tight gapping needed for overblowing to be a nuisance, causing choking if I play the reed hard). I can and do adjust the tremolo harps I sometimes use.