Bach 1½C vs Curry 3 C.
The Bach 1½C has a wider cup diameter, the Curry 3 C. has a larger throat opening.
Cup Diameter
The Bach 1½C has a cup diameter of 17.00 mm / 0.6693 in compared to 16.89 mm / 0.6650 in on the Curry 3 C. — a difference of 0.11 mm / 0.0043 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Curry 3 C. has a wider throat (3.70 mm / 0.1455 in vs 3.66 mm / 0.1441 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.