Volume: Loud. Just a shade quieter than my Copeland.
Responsiveness: Fast. It sounds a little choppy cutting the high octave D, but a number of whistles I've tried with higher back pressure can do that. I usually solve it by venting the high D when I cut, but didn't do it in the recording, so you could hear it.
Tuning: The intonation on this whistle isn't the greatest. In the first octave, the E and the G have to be played with a bit lighter breath to be in tune, and the F# has to be really pushed. In the second octave has similar breath requirements, and additionally the B is about 25 cents flat, no matter how hard I push it. I could play this with others once I got used to the breath, but I'd have to avoid any tunes that hit the second octave B. At that volume, you really don't want to be 25 cents flat from the musicians around you!
This is a D+ whistle meaning that there's a seventh hole played by the pinkie of the bottom hand. If you ignore that hole, the whistle plays like a D no problem. Cover it, and it will play a C, for those odd songs that need it. This one plays the C about 22 cents flat. That's pushing it near the octave jump. At the expected breath, it's closer to 28 cents flat.
C-natural: OXXOOO plays a C-natural that's absolutely perfect with the expected breath.
Hole size and placement: Except for the extra 7th hole, the hole are centered on the whistle body, and fairly evenly spaced. The D hole is a little larger than average, but about the same size as the E hole, so it didn’t give me any difficulties. The bottom C hole is a little further down, and offset for easier reach. Since I play leftie, it's offset the wrong way for me, making playing it awkward. You'd want to be sure and let Paul know if you needed it offeset for lefties when ordering. Because the whistle is longer than a normal D, and has an extra hole, it was a bit akward to play at first until I got used to the way it felt in my hands. I got used to it pretty quickly though.
Air volume requirements: Average. I don't really find myself noticing that I can go a long distance without breathing, or having to take a breath sooner than normal.
Air pressure requirements: medium to high in the 2nd octave. You have to really push to keep this whistle happen in the high A and B. This is a lot more like the harder blowing Thin Weasels I've tried than the Cocobolo Busman I had a while couple of years ago.
Clogging: Being acetal, I was surprised to find this whistle clogged quickly. And it doensn't take much to make the whistle cut out. I'd definitely want to give this whistle the Duponol treatment if I were keeping it.
Wind Resistance: Low. This whistle plays in a breeze, but anything above that and it cuts right out, especially if it's a cross wind (rather than being at your back).