Volume: Louder than average. The first octave is about as loud as my Copeland (unless you want to play it in tune..then it's the quietest whistle I own..see below). The second octave is a fair amount louder than the Copeland.
Responsiveness: Fairly responsive. No problems there at all, though I find myself less nimble tonguing rapidly on whitles that require higher backpressue. That's my failing, more than anything.
Tuning: Out of tune, both with itself and with others. The first octave on this whistle is 30 cents sharp when I have the tuning slide pulled out as far as I can pull it without it getting loose and wobbly. The second octave starts out in tune, but flattens as you go up the scale, until the high A and B are about 30 cents flat. This makes it fairly impossible to use this whistle with others. If I way underblow the the instrument in the first octave, so that it's barely playing and the volume is way down, I can bring it into tune, but this doesn't seem a very realistic solution to me, since the volume disparity between octaves becomes immense.
C-natural: like the rest of the instrument in the first octave, OXXOOO is sharp, by about 35 cents. OXXXOX brings it into tune, but then you're out of tune with the rest of the whistle.
Hole size and placement: The holes are nicely sized and fairly evenly spaced along the whistle. The F# hole is smallish compared to the rest, and none of the holes are especially over-large.
Air volume requirements: Higher than average. I find myself running out of breath a little sooner on the whistle.
Air pressure requirements: Higher than average in the second octave. It takes a bit of push to keep things square up there, especially once you get up to high G, A and B.
Clogging: On cold mornings, I found this whistle clogging after about 15 minutes. Just standard clogging behavior: the whistle would feel a little more backpressure and slowly cut out. Blowing the whistle out was fine. When in a warmer environment, I had no clogging problems at all. I probably wouldn't bother with Duponol on this whistle.
Wind Resistance: Moderate. Holds up to a decent beeze, and you can sort of push it in even a heavier wind.