As great as it sounds using physics and big terms to explain something it all comes down to the body. If you're charging pow on a stiffer board, especially choppy pow whether it's heavy mashed potato style or even pushed around light stuff you get the whump factor. The nose hits it and bounces off it still sending vibrations upward into your body.
You need to use the knee flexation to absorb it. Think of it like riding moguls you don't go into it charging and expect the board to just hit the mogul and ping off it, you have to bend the knees and pump the bump keeping it going. Doesn't matter how stiff of a board you have with all the dampening agents in the world it's more knee motion than anything that's going to get you through choppy snow.
If you really want a board that's going to get you through it get something with either Pow Rocker or that is more powder specific with reverse camber. You're no longer fighting the loading and unloading of the camber and with the nose being elevated more it will help you to roll over the top of it.
Actually physics has the ability to describe any system in motion (which means you could technically derive chemistry if quantum mechanics was complete (it would just suck a lot (you would have to use Feynmann diagrams which get complicated very fast)). What I explained earlier is what happens to the board and why riding a softer board will make riding through choppy pow more tiring. When you ride something like choppy pow you obviously have to absorb the impact from the chop, and you also have to at least somewhat plan you line for an area of less chop.
Your knees are the best damping system there is, they have the ability to actively adapt to conditions and absorb crazy amounts of energy. I was assuming that who ever is riding has the common sense to understand that you have to use your body to absorb the larger impacts.
What I was trying to explain earlier is what I thought the question was asking, which is more or less how can I make riding choppy pow less tiring.
If you are riding moguls a stiffer deck will help too, because (same argument as before) when you land the divot of a mougle your energy will be transfered form going into the divot to the path of lest resistance (aka hopefully where you want to be going) quicker which means there is less time for the kinetic energy (energy of motion) to be transfered into you in the form of you absorbing the impact with your body, which intern translates to you having to absorb less energy which means you don't get as tired.
Also I asked google and flexation isn't a word.