Volume: Slightly above average. The whistle is perhaps not quite as loud as a Susato, but it's definitely louder than your standard inexpensive whistle.
Responsiveness: Quick. I didn't have any problems playing this whistle up to speed.
Tuning: In tune along it's range. The first octave (especially the D) requires less breath than you'd expect..it's easy to blow sharp. here's a big gap between first and second octave on the breath, and you have to push the top B to get it into tune. But it's not as much as a fight up there as some whistles I've played, After a while, I got used to it.
C-natural: This was the only negative I found in the entire whistle. OXXOOO and OXXXOX both produce a sharp C-natural, and OXXXXXO produces one that's flat. I couldn't find a cross-fingering that produced an in-tune c-natural, so this whistle will require half-holing. I probably wouldn't even bother with half-holing on fast tunes, but the fingerings are 10-20 cents off, so I would definitely have to on slow tunes where the dissonance would be clear.
Hole size and placement: The holes are well rounded, evenly spaced, and a bit on the smallish side, making them easy to cover, but not as easy to half-hole.
Air volume requirements: A little higher than my inexpensive whistles. I do find myself taking breaths more often on this whistle, but not to the extreme. Perhaps a couple notes earlier than I normally would.
Air pressure requirements: Low in the first octave, and higher in the second octave. You really should be comfortable supporting a whistle with your diaphragm and pushing a bit (like with Overton whistles) to get the most out of the second octave.
Clogging: The whistle never clogged up on me, though after extended playing it did lose a little responsiveness due to moisture. I probably wouldn't use Duponol on this whistle unless it was my primary instrument.
Wind Resistance: Incredible! I played this whistle a couple weeks ago when we had the big thunderstorms and tornado warnings. The wind outside was strongly gusty and unpredictable. I think I only lost one note to the wind while playing tunes in those challenging circumstances.