I only know the Z, and love it.
My old instructor always borrowed it for lead in jazz orchestra parts, and is used by one of the ToP guys (at least one, anyway).
for me, i do not find it stuffy, slotting is very tight, thus not loosey goosey allowing for some freeer "play" and bending.
for the price you can get one on ebay, they are a lot of horn for the $, but certainly do try one and see....it screams.

All that said, I like my Selmer and Conn 40B better for tone, etc...but the Yamaha is much more accurate in slotting and gitting the right notes