I keep typing up a post and then deleting it. I’ll put on my flame suit and see if I can manage to post this one.
I was also in the pursuit of ultimate comfort and dreamed of my rig floating over washboard roads and ignoring speed bumps as I sipped a latte. I did research on the different valving strategies that you mention: digressive, progressive. Did test rides in Icon equipped vehicles, King equipped vehicles. Learned about the natural frequency of a spring mass system, the roll center, anti-squat, etc etc. eventually I decided that the BP-51 bypass shocks were what I needed for pinky-up comfort. I put them on and they were… different from the stock suspension. On the highway, the body control was amazing and you could feel the dampers working. But speed bumps at low speed would launch any spare change or sunglasses into the headliner. So I went back to the drawing board. Oh yes, what I really need are custom valved adjustable shocks perfectly tuned to my vehicle, my payload, my tires’ unsprung mass. And then my backside would be perfectly happy no matter the terrain. So I gave my precise parameters to Accutune and asked them to make their valving as soft as they could for ultimate Cadillac cloud comfort. So I installed them and they were… different. A little less hard-working on the highway and a little more forgiving on speed bumps. I drove each of those setups for months, years, hoping maybe they’d loosen up or the coils would “settle” and nirvana would be mine. But they kept riding the same. I always kept my BPs and DSCs at the softest setting and still wished for softer. Eventually I returned to the stock dampers with squishy rubber lower mounts and valving suitable for a lightly loaded vehicle not in pursuit of Baja gold.
If you have steel bumpers, trekboxx, roof top tent, armor, then the aftermarket shocks may become more comfortable than the stock dampers trying their best, but wallowing like a ship on rough seas. I rode in a vehicle on Dobinsons MRRs with the aforementioned weight, and that matchup proved to be the most comfortable next to a stockish weight and stockish suspension.
All this to say that Kings have an application, but it’s not ultimate road comfort.