I've never thrown a cryztal buzzz. I'd love to get one. They seem pretty, but not really a workhorse.
I have 2 Z and 2 BigZ. One Big Z is overstable (though not as much as my GloZ Buzzz) and the other is less so. The various big Z discs don't always seem to have the same plastic. I posted a picture somewhere (sorry that doesn't help), but the more stable BigZ is much more opaque, while the less stable is more translucent, seeming closer to Z.
So, my 4 discs, from most overstable to least:
1) BigZ, opaque, 178
2) Z, Fly-dye, 177+
3) BigZ, clearer, 177+
4) Z, tourney stamp, 174
I love 'em all. They're more similar than different, but I typically bag 3 and 4 right now.