I have an Overton Low D and also a Low F. My low D actually could be better, but I haven't dared start filing it or anything, my low F whistle is lovely. I mainly use them for slow airs. To play jigs and reels would be more difficult as I don't have enormous hands, so it is hard to play fast. I use the flat pads at the end of my fingers, as my hands are not big enough to use the next joint, and I use my little finger on the lowest hole (as it is too much of a stretch for the one I normally use on a small whistle). I also play a Breton dance tune 'Dans en Dro' on the low D. Did you say your whistle was blue??! (mine are plain metal-coloured)