I think the Yanagisawas can be made into really great pieces... I have tried them both out-of-the-box as well as refaced, and although they aren't that great when they're stock (run of the mill), with a slightly longer facing than stock and a standard reface they can be really great playing pieces. They have small chambers like the Soloists.
Honestly, although the details of the core of the design might be a bit different from one mouthpiece manufacturer to the next, a whole lot of the hard rubber soprano mouthpieces out there nowadays are just rollover-baffle squeeze chamber designs, much like the Soloists were. What I'm saying is that I really don't think you have to get a Soloist, or spend over a hundred bucks, to get a really nice blank to work with. When set-up with a good facing curve and tip opening for whatever strength jazz cut reeds you prefer, the HR Otto Links are great playing pieces, I think the Meyers are really good too, the Yanagisawas are really good, and the Bari HR's are really good. The Yanis can be a little more expensive new, but you can find them used for good prices.
I've found that with a flat table, a medium-to-long facing length, a moderate to medium-open tip opening somewhere between .060"-.070", and a radial curve, these types of pieces can be made into really nice, easy to play, warm sounding players. Sometimes, the windows might need to be moved backwards a little bit too to better match up with the length of a vamp of a reed, I found this to really help on a Yani I was working on recently.