Volume: This whistle is moderately loud. The first one was way too quiet--it couldn't be heard in a near empty bar with no other musicians playing. This one is much better, and I expect it will hold it's own in sessions.
Responsiveness: This whistle is fairly responsive. It allows me to execute cuts and rolls without a problem.
Tuning: This whistle is in tune at A=440 with proper breath control when the whistle is cold. The only complaint here is that the D is a wee bit sharp (15 cents) using the same breath as the rest of the notes, so you have to come down a little for that one note. But since it can be blown into tune without too much lung gymnastics, it's just an idiosyncrasy that you can get used to. All whistles have them.
C-natural: OXXOOO produces a slightly flat C-natural with the expected breath requirements. OXOOOO is much better.
Hole size and placement: This whistle has holes are average sized. Hole positions are similar to the Clarke Sweetone in size and placement. I don't see it as an issue for anyone.
Air volume requirements: Slightly Below average. After narrowing the windway, I find I can get a lot out of a breath on this whistle. The first one took a lot more air.
Air pressure requirements: Average. No super strong push required.
Clogging: Copper tends to collect condensate quite a bit, and this one's no exception. The first one was much better at this, but I imagine that it's because of how much air was whooshing through that wide windway. This whistle will definitely require some anti-condensation measure.
Misc Notes: This whistle really likes you to stick it straight out of your mouth and blow straight down the windway, and David confirmed this characteristic with me in correspondence. No playing at an angle with it stuck in the corner of your mouth, like I usually do.