Although the concept is interesting and we used to use the pins [5 pin] on kind of the same concept by knowing the approx chest measurements of the animals in your area...for example a mature elk with a chest of 30" if one held the sight and pins on the bull and you held the 30 yard pin on the back of the elk and the 40 yard pin was on the bottom of the chest, then you knew the bull was at 50 yards...etc
This may be an asset for new shooters but for an Old dog...this is one trick that would screw me right up because aiming with the pin to miss [below the animal ] would not work as instict would take over and I would have to put pin in vitals...
Shooting outdoors a lot with 5 pins can improve your juding distance very well also and I have always depended on that...
but I like the concept and it may work for some...I just know its not for me personally..
Neil