I seen several posts from disappointed fatbike owners and smaller e assist setups. Those wheels/tires are big and heavy and have a lot of drag. You need a some real power to not be a slug on one. Much less in sand or snow. I think Bafang is the right choice for a fatbike.
highly doubt youll need the bluto. i find my neo xtrem with front shock a much rougher ride than my bikes direct boris x7 with no shocks. the tires make for quite a comfortable ride. you could always add a thudbuster post afterwards too.