I'm a desert / dune guy myself...
Out of all the high end shocks options… it’s the Fox 2.5 RR with DSC adjusters AND high flow piston upgrade I want the most.
King does an amazing job of marketing to the desert crowd and for the longest time wanted a set for myself but the more I learned the more I started leaning towards Fox. For me it was primarily the way the adjustment controls worked. King adjusters only control high speed compression, whereas Fox you have independent adjustment for high speed and low speed compression.
Considering traversing dunes has a lot of low speed compression events, I figured that would really help maximize tuning when driving around and having a lot of weight shift from wheel to wheel.
I am currently running a 6112 but looking to upgrade, they work great until you start to push them harder, specifically in high speed compression events it feels like you blow though the entire shock stroke and it’s easy to bottom out. I don’t think the digressive valving works that great out there, which is another reason I decided against ICON when I upgrade. King and Fox both offer progressive valving, and as shaft speed increases, so does the resistance. Seems to make sense to me.
Unfortunately the Fox shock are the most expensive out of the bunch, but I feel they might be worth it.