I use the chrome plated nickel for playing with bands; fiddle/guitar/bass, because the hard clear tone penetrates better,especially in the second octave, and makes a good contrast to the other instruments. The brass gets lost.
Also have found it a struggle to properly mike a whistle; it has to stand on its own somewhat. So. louder is better.
I use the brass when I am playing along with a singer, or sometimes with just a concertina, because the softer, mellower, breathy tone matches those voices better.
Blessings,
Barbara