I put quite a few miles on a Fatbike that I had access to for a couple of years, even going through several miles of 6+ deep snow with little problem. It can be a serviceable trail bike, but I prefer my FS MTB for that. Recently, I put a 2.35" tire on the front and a 2.5" on the rear (the widest my frame and fork will accept without mods) and now I use it on roads, trails, and even the beach. I lost a couple of MPH on the road compared to the 2.1" tires I had originally, but the tradeoff is well worth to me.
Good luck with whichever way you go. You might want to look into the PLUS bikes before you pull the trigger.