In my experience whistles vary more by maker than by size in the matter of air consumption. Burkes across the board (I’ve owned them in several sizes from low D to high D) take more air than most; my Burke “session bore” high D took about as much air as my MK and Goldie low Ds.
My Alba bass A takes no more air than my Burke low Eb.
That varies from maker to maker. My Alba low C has finger-spacing more comfortable than some low Ds I’ve played.
In my opinion Susatos get better as they get lower. I had a keyless Susato low C that was a great player, and Susato low Ds are very good. Both were keyless by the way.
I think the keyed Susato low whistles are great for people who are ergonomically challenged by low whistles. I do wish that Susato would use their existing low whistle technology and make much lower whistles. I’d love to have a Susato keyed Bass D.
But I’m with you in that IMHO a Susato low D isn’t in the same category as low Ds by Goldie, Overton, MK, Lofgren, Reyburn, Reviol, and Burke (to name a few).
Yes it struck me as strange the first time I heard people talk about “mezzo whistles” but Italian words are standard in international music terminology. Their universality makes them useful. If one prefers using the English that’s fine too, though “middle G whistle” sounds a bit odd to my ears. (I don’t know why; “low, middle, high” seems perfectly logical.)
BTW the word “music” is from Greek, “instrument” from Latin… we wouldn’t be able to have much of a discussion about musical instruments if we had to stick to native English words.
It might interest some to know that Leo Rowsome, an Irish player and maker of an Irish folk instrument, used numerous Italian musical terms in his tutor for the uilleann pipes including mordent, appoggiatura, and acciaccatura.