I have a non Trek Fatbike and it’s a relatively new experience for me as we’ve only been together for a few months but I live very close to South Downs Way so me, bike and mud spend a lot of time together.
As others have said tyre pressures are absolutely key, some tyres can feel pants and then a 2psi difference transforms them. I ride the Maxxis FBF and FBF and I am stunned at the muddy climbs I can just peddle up, tmy legs will give way before the traction not quite so good on the more multi purpose tyres it came with but have kept those for summer based fun.
Does it still slide in mud hell yes, does it slide as much as a “normal bike” in my experience not as much but caveat depends on mud types etc Most of the time I’m heading towards the muddiest, steepest trails I can find 🙂 Mostly giggling as I do at daft bike (and only bike) as I peddle upwards.
Can’t recommend a fat bike enough, but you do need to adjust your head to it a little with tyre pressures, everyone asking you about it everywhere you go, your mates taking the piss initially and then asking if they can have a go etc.
James