GRZ Black RAW with 250W Bafang motor, 12 speeds and 26 x 4.8 tires
Compared to my non-electric and non-fat-tire hardtail mtb this thing is an absolute tank. I originally only bought it so I could ride year around in the snow too but I love it so much that I basically stopped riding my other bike altogether. For riding in the snow it has to be electric assisted unless you truly want to suffer. Even now I almost never see any other bike tracks on the trails in the winter than mine. Yesterday I plowed thru a trail with half meter deep snow drifts. Even the hikers whose tracks I was following turned around.
In the summer time it has infinite traction and it just rolls over anything you throw at it. You can even ride it off the trail in the brush over soft moss and boulders no problem. The only better all terrain vehicle than this would be a horse.
I find that temperature affects it a lot more than the amount of snow. Even in deeper snow it's not so much power you need but the ability to maintain momentum. When you stall it's generally because you lose grip and thus speed also. You can't really ride a fatbike in any deeper snow than you can a regular one. The benefit comes from the wide tires that act as snowshoes and prevent you from sinking in while also providing a lot more grip compared to narrower tires. With good balance you can ride on snowy trails that are really difficult to walk on.
I'd say that in summer I can do a 45km trip of mixed single track and gravel road quite comfortably but in below 10 degrees celcius we're speaking more like 25km.