That "giving back of weight" is confusing to this Wu stylist mind of mine. I have found a few places where it is applicable to combat, however in every one of those instances I have found that the weighted pivot works equally well, and in some cases far better.
I guess it's a case of what you are used to. I have been practicing weighted pivots, both in Wu style and previously in "traditional" Yang style, for twenty years. The "shifting back and forth" was not taught to me, by anyone, until three years ago when I began training YCF style.
I am still working on it, though, and have not condemned it by any stretch. I am working on the uses, practical applications, of this "giving back of weight" before movement. I find it fascinating.
It is obviously the precursor of the Wu style "lean". YCF stylists shift, Wu stylists lean. You get to the same place, but to one who is used to instantaneous movement it seems slow and awkward to me.
My YCF instructor can move like lightning this way, however, and I am working on the subtleties to get me to that point.
My former associates in Wu style find the concept fascinating, and just as confusing as it is to me.
As with the "movement from the waist" for push hands as opposed to "movement from the hip" you get to the same place, but in an entirely different manner.
Fascinating, fascinating differences.