I weighed two Hyper Z's on my wife's food scale. I weighed them two ways. Once with the weight of the whole bat on the scale, then again with just the barrel on the scale and the knob on the counter (I call this swing weight).
Results: Factory labelled 28 oz - Actual weight 27.76 oz. - Swing Weight 22.96 oz.
Factory labelled 27 oz - Actual weight 27.32 oz. - Swing Weight 22.42 oz.
for comparison:
Factory labelled 27 oz Dudley Lightning 13" EL - Actual Weight 26.81 oz - Swing Weight - 21.27 oz.
There is some lack of scientific precision in these measurements (I did do them on my wife's food scale), but I was careful to position each of the bats on the scale in the same position. The swing weights confirmed what I had experienced in using the bats: The Hyper Z was considerable more end-loaded than the Dudley and anything else that I own.
I like the Hyper Z, but would choose a 26 oz if I were to order a new one.