Tone: This whistle has an extremely 'fat' and full tone, with a very miniscule amount of windiness in the tone to add complexity. At first, I thought it sounded a lot like my Abell (which is one of my most dearly loved whistles). But when I played the Abell and the McManus back to back, the McManus whistle sounded so much more full, and the Abell sounded thin in comparison. That's pretty amazing, since the Abell does not have a thin tone.
Volume: Loud--even louder than my Abell. I asked Roy about this, and he stated that he felt that there were enough quiet whistles in the market, and he aims for good volume in his work.
Responsiveness: Crisp and responsive. I have no problems at all with this whistle.
Tuning: In tune up the scale. While it's easy to blow this whistle in tune and be stable, I can also exert a little effort and push each note ± 20 cents with breath control, allowing for emotional expressiveness. That said, I did have one surprise--venting the 2nd octave D (OXXXXX instead of XXXXXX) is about 17 cents sharp and requires a bit of work to bring under control. This is only a minor quibble for me, as the fully-closed second octave D is completely in tune with the expected breath.
C-natural: The standard cross-fingered OXXOOO makes a perfect c-natural. Any other semi-standard fingerings do not prooduce a c-natural even close to being in tune. So if you're used to using a different configuration, it's probably best to half-hole this whistle.
Hole size and placement: The holes are well-centered. The sizes and placements are extremely similar to my Abell, with the slightly enlarged E whole and slightly smaller F# hole. This configuration makes the holes nearly evenly spaced along the whistle body. The hole edges are also well polished, making them feel nice and smooth under your fingers.
Air volume requirements: Slightly high, but nothing like a Clarke original or a Shaw. When comparing to my Abell, I run out of breath just a couple of notes more on it. That said, I generally take breaths lonng before I get to the point of desperation, and when I played this whistle in session, I didn't have any issues at all taking breaths at my usual spots.
Air pressure requirements: Slightly high, taking a touch more pressure than my Abell. But there's a satisfying amount of backpressure that goes with it, letting you lean into the instrument. And it's not so high that I feel like it's a chore to play the instrument, like some others I've played in the past.
Clogging: Good. I played this whistle for hours at sessions, without a problem. A couple of times, the whistle would start to feel a little wet, but a quick cover-and-blow would solve the issue and I never once got waterlogged to the point that it wouldn't play reliably.
Wind Resistance: Moderate. I could feel the whistle wanting to cut out when a moderate breeze blew directly across the whistle, especially in the bottom 3 notes. If you were to play this outside in a stiff breeze, you'd probably have to do a bit of wind management. I expect that I could play it in a decently windy location if I kept my back to the wind.