Rocketman has got the skinny on shotgun handling characteristics better than anyone I've ever sat and talked with. The biggest revelation to me, years ago when Don explained it to me as he spun a little .410 S x S I had been given, was that overall weight is not nearly as important to handling as is where that weight is located in the gun.
If the majority of the mass is in the action, and it has short barrels, struck well off at the muzzles, and not very dense wood, it will move quicker between the hands. Or, have a low moment if inertia. OTOH, the little .410 he spun was quite eye opening, with it's 28", fairly thick barrels, longer than usual for a .410 buttstock, and alloy action, the weight is more "out on the ends", you might say. This makes it handle like a much heavier gun, and probably explains the reason it is so easy for me to shoot well. He actually said the "numbers" almost perfectly matched that of a nice English 12b game gun.
When the weight is on the "ends", an object responds slower to a change in it's motion, or lack of motion. When the weight is concentrated in the middle, or between the hands, it responds much quicker to that change of motion, or state. These guns we call "lively", or even "whippy".
My 31 1/2" Perazzi is stocked in fairly dense walnut. Even though it weighs 9 lbs. + it handles like a dream for me. The way it moves belies it's overall weight. No one that has ever shot it thinks it weighs as much as it does.
Just some of my thoughts too, gunman.
SRH
