I have a Dixon low D Duo, and like it well enough (easy to play, moderate hand stretch, quiet) but it's almost
too quiet for my taste, and the low D and E are noticably weak.
Nice for late-night playing, especially slow airs. Not really suited to even slow jigs or hornpipes, though. You *can* play it faster with the flute head, and it has a LOT more volume that way; perhaps because of this I almost never play it as a whistle any more, even though I'm a more skilled whistler than flutist.
But I play my Serpent Low F all the time. Takes a minute or two to warm up, but then it's stable all night. Solid bell note, lovely voice, very even volume across two octaves. And as easy to play high-whistle style as using piper's grip (I have medium-size male hands). Had a chance to do a direct comparison with a couple of Overton Low F whistles a couple of weeks back (SF get-together) and thought that it stood up pretty well to that competition (that is, I wanted one of EACH
instead of a trade).
But the trade-off is cost - a Serpent costs twice what a Susato or Dixon does. (If only about half the cost of an Overton). I think a good whistle like an Overton, Burke, or Serpent is well worth it if you're serious (or just need some volume). If you don't need the volume, the Dixons are decent whistles (and I'd choose a low Dixon over a low Susato).
