alright ill chime in here since i been down this road recently (last year actually). Last fall i bought myself a specialized fatboy setup with 4.8 (iirc) tires (full rigid) with the intent to keep it as an extra/snow/sand bike. I rode it exclusively in south jersey sand (mostly allaire) and in the fall i bought a stache (29+ hardtail) which i proceeded to ride everywhere i had previously ridden the fatbike. This winter i made apoint of riding the two of them back to back in the snow to gauge how they handled differently. My conclusion was that the fatbike isnt for me, i prefer the plus bike for numerous reasons (obviously its lighter, but that came to me later). Its more nimble, more versatile, more responsive and (IMO) more fun than the fatboy . . . .
obviously this is something you need to try out and figure for yourself, but i much prefer the stache to the fatboy. and have not noticed any issues with overall width on either bike (i do get occasional heel rub on the chainstays of my 27.5+ fuel, but thats unrelated).