We just took delivery of our new fifth wheel. It has a TrailAir pin box on it. Never had a fifth wheel before so I'm not the best judge (I'll leave that to the experts), but just watching how it works while driving (well, I did steal a look or two in the rear view mirror

) it looks like it's doing what it's supposed to do.
Smooth ride all the way, no harse pitching experienced at all. I can't say what it does for chucking, though as it primarily works in the up/down plane only.
MoRyde was the other pin box alternative we were looking at (on a Grand Junction). It seems like it would be better for fore/aft damping, but not as well for up/down damping.
Can't have it all?
Juan