I would agree that a good fat bike weight and tire quality wise vs a cheap one makes a world of difference. Before I got a good deal on my fat bike I was eyeing a 29" x 3" ECR which I think would be even a little better than a dedicated fat bike but the cost was a little to high for me at the time.
My thinking in the last couple of years has been to find a combination that covers the wide spectrum of riding conditions I want to take on. Fast road tours to off road exploration. We often talk about the "one bike to rule them all" but I don't think that's really possible. The difference in posture between aggressive trail riding and fast road riding dictates two very different geometries if one wants to be even a little close to optimal.
The conditions I like to ride/tour in are:
Road
Gravel
Trails
Singletrack
No track
Mixed terrain
So I decided to go with two bikes to cover that spectrum.
My first is an endurance road frame that runs 700c x 28mm or 32mm slicks but can also fit 35mm treaded tires. This covers the gambit of road and gravel grinding.
My second is a fat bike that can take either 26" x 4.6" or 29" x 3" with a second wheelset. This covers rough gravel, trails, singletrack, no track and mixed terrain like bog, sand and snow. With a suspension fork it would also do technical downhill mtb but that's not really touring territory and the suspension fork would take away from touring I think.
By using a modular bag system that fits both bikes I can add or subtract bags to scale up or down depending on duration of trip and how much stuff I want to bring. I can do day long centuries or trail riding or multi week tours with each.
By good fortune both seat posts are 27.2 so I can invest in a decent dropper post and swap that between bikes too if I want, allowing for an aggressive gravel grinder or better up and down trail bike.
