Volume: This whistle is on the low side of medium. Just right for your average session. On a loud session, only the folks immediately next to you will hear you.
Responsiveness: I originally wrote that the response on these were fast. And they feel fast. But after recording myself, I have to downgrade the response to "moderate." Sweetones don't feel sluggish, but in general tend to sound less crisp on the fast execution of ornamentation like rolls and crans. They also sound less crisp on fiddle tunes that bounce back and forth between the first and second octave (like Drowsy Maggie, Glass of Beer or Tam Lin)
Tuning: The whistle isn't billed as tunable, but I found that the head was not glued on. Because of the soldered seam, it took a little work to get off, but not too much. With a little adjusting, the whistle was A=440. From there, it was in tune across the entire range. Another reason I fell in love with this little beauty.
C-natural: OXXOOO produces an in-tune c-natural.
Hole size and placement: This whistle has holes are average size and placement. There are no weird spacings. If you can play a soprano D, you can play this one.
Air volume and pressure requirements: This whistle's a very easy player. You can jump the octave easily, and it doesn't take much breath. In fact, this was the first whistle that I really enjoyed hitting the second octave on. Most old whistlers forget what it's like to be new, and dreading playing in the second octave. This whistle was really easy in that regard compared to the others I'd tried until then.
Clogging: This whistle is middle-of-the-road when it comes to clogging. It clogs after about 20 minutes, then I just blow it out and keep going. Plastic mouthpieced whistles are probably the easiest to maintain in this regard. It just never slowed me down much, and I played a Sweetone as my only instrument for years.