Baritones in a brass band serve a distinct purpose depending on which part you're playing. Your role in the brass band should be a factor behind which mouthpiece you select for your instrument.
This write-up by the Dublin Silver Band does an excellent job explaining the role of each instrument in a brass band!
James Kircoff
Genesee Wind Symphony - principal euphonium (Adams E3 Custom .60mm yellow brass bell w/ K&G 3.5)
Capital City Brass Band (2019 NABBA 2nd section champions) - 1st baritone (Besson BE956 w/ Denis Wick 6BY)