Few people use an F exclusively for things like the Berlioz Requiem and Bydlo, but try to use it for other circumstances (brass quintet, ballet/opera), and other cases where range requirements are very moderate. Because of that, I prefer a mouthpiece either the same size as for a CC, or very slightly smaller, but with a shallower cup. I use a Laskey 30H on CC, and a Laskey 30F on F. The cup diameter is the same, but the cup is shallower. As an alternative, I have a Laskey 28F, but seldom use it.
Many years ago I used a distinctly smaller cup on F (a Mirafone), and found that it had a negative impact on sound below 4th line F. At the time I considered the F more of a specialty instrument than I do now.
With age comes wisdom.
