My previous 5th wheel had the Demco GlideRide pinbox extension. The current 5th wheel has the TrailAir with the fore/aft compliant loadplate as in the Demco. As far as fore/aft chucking is concerned, I don't notice any difference between the previous Demco and the current TrailAir, but the TrailAir has the advantage of providing compliance for vertical shock loads.
The new 20K rated Companion 5th wheel base is much more substantial than the previous 18K rated Companion base. I upgraded my Companion base to the 20K rated base for the new 5th wheel, and there are many design improvements including a completely new adapter post and bolting arrangement to attach the Companion base to the adapter post. The upgraded Companion works fine with the new 19K GVWR 5th wheel.
Rusty