Not necessarily... a Vandoren 2½ on a stock Jupiter 4C mouthpiece was too soft for me to play on, but really sings on a Selmer S80 (C*)
Conversely, a Vandoren 3 plays fairly well on the Jupiter 4C, but is much too hard on the Soloist.
It's due to the tip opening, I've been told. The "real" regulars here can enlighten you about that, I suppose...
