Does the fat bike ride on snow compare to something like mild mud, or sand, or... ?
I tried to ride on the snow with 2.25 tires recently and it is much harder to fight the snow than anything else.
It is like if I was braking while pedalling.
Never ridden on sand with it, nor mild mud. But I can see mud being hard since there is a ton of tire surface to stick to and make your bike weight twice as much as normal.
Riding through a bunch of unpacked snow is hard. There is enough snow and people with fatbikes, that we have a group that maintains the trail and packs it when fresh snow comes. Once packed down, it freezes and sets up awesome. Once the base of the trail is good, even if it snows a couple of inches of fresh, you can still ride it due to the solid base.
With as much trail maintenance that we do on our trail we require minimum of 3.5" tires, otherwise there is a large risk of putting a deep rut in the groomed trail and takes a lot of work to fix. My 4.8" tires I can run at about 4psi. The first ride it felt a little weird because you can feel the tire flex/move on the corners, but I had ton of grip uphill and down.
The groomed snowmobile roads are great too. Gives me a ton of trails to go ride base hours for 2-3 hours.