The Soprano is a stunning instrument and can be a lot more versatile then many believe. The timbre of the Soprano is quite nasal and incredibly sweet, and of all the saxophones does have the most innate character. Therefore, the choice of mouthpiece on a Sop will either lean into these characteristics or try and push the Sop in a new direction. Something to bear in mind also is that a Soprano mouthpiece is very small, so there will not be a huge variation in chamber and baffle types. The material in this case, will have the most pivotal effect on the sound you produce.