OK, then ... My opinion is that the premise of your original question is flawed. So insisting on better answers will not necessarily give you better answers. Sorry.RPereira wrote:But don’t go far from the topic please…
As folk music, Irish trad is constrained and conditioned by the main instruments used to play it (fiddle, pipes/winds), and by the tradition itself. The other musics and instruments you mentioned aren't limited in the same way, or in different ways from ITM. So there are no predictable main keys for all of them. Whistle isn't a common instrument for these musics, so there are no common whistle keys, and there's no good answer.
To force whistle outside its native diatonic idiom, you need to handle chromaticity, modulation, and in-between keys. Sure, it's possible, but may require extreme fingering skill and/or a set of whistles in every key. It's a procrustean* effort.
[* ask Nanohedron! ]
The non-D whistles you hear in trad(ish) recordings by McGoldrick, Finnegan, et al. are chosen mostly for the variety of timbre and pitch they bring to the music. They pick music that suits the whistle, not vice-versa. They play them as transposing instruments in the usual D fingering patterns and trad keys. And that's an approach that you can use, too. Good luck!
