Ive had my Fatty for 6 weeks now and put just over 700 miles on it, not touched any of my other bikes since I got it.
I regularly look at the 2.4″ tyres Ive got on my 29’er and think they’re really skinny!
I have now got a rear rack and my full length carbon mudguards on it, and it just does everything I ask of it.
Only thing with fat bikes, big fat tyres do NOT like thick mud, for obvious reasons.
While it can be a pain trying to get grip climbing on mud, when you start to go downhill on mud, its like you’ve just had 40 pints and jumped straight on the bike for a ride, but its so uncontrollable, it is actually very funny trying to stay upright, well I find it funny anyway!
But, as others have said, you can just get a spare set of 29’er wheels made up if you wanted an easier day of riding.