G'day ChetW & all,I bought the 3 small Susatos (D, C and A) a while back. Everyone (including the seller) told me the A didn't work well (and I could bring it back if I didn't like it)... Worked well for me!
Now I have a low D - it runs right through its 2½ octaves quite nicely ... for me anyway.
I have been making a few (dozen) low D whistles lately (to investigate tone-hole placement alternatives for small hands/ small finger). I thried a few with the curved windway configuration but, because I was short of material for the outer tube, I had to make them very short.
Kathy Potter, my flautist / whistle player in Backblocks Musicians (who has a classical flute background and has approached recorders via tin whistle) found that the one she liked best was one of the short mouthpiece, curved windway jobs. Kathy says this gives her a high degree of control. Of course, Kathy blithely plays something you or I would say was off pitch ... and corects it as she plays!
I guess it is a matter of what suits what player.
Regards,
Bob Bolton