Hey, Mark!
Nah... that's a great post about the Jazz! You're in the right forum... Callet... and, strange Jazz/old Jazz... works for me. You describe the horn well. It does "like" a smaller mouthpiece to really dial things in. Not necessarily diameter-wise, but cup-volume-wise there's a better balance with the horns resistance, or lack of resistance, with a mouthpiece that has less cup-volume.
Callet horns do seem to have an overdrive, too!
Thanks, Mark!
Best always,
Bruce