personal choices ... personally, I road a long, unpaved, rugged, rail trail last year. read reviews that regular road bikes could manage it just fine, met a cpl guys on the trail who swore the trail could only be ridden on fat bikes. I managed OK doing it with a hybrid with larger than normal tires but really enjoyed in on a regular 29er style MTB. I've read where ppl think fat bikes (4"+ tires) are hard to pedal & slow. so far, I can manage the trails near me with 2.25 tires so I stopped considering a "fat bike". they still look intriguing & I'd love to do a favorite 2-10 mile beach hike w/ a fat bike instead, to see if it's better than walking that far