I'd agree with the comment that the fatty is less work than a skinny in some conditions. Muddy trails where a narrow tyre digs in and is a real chore are floated over with the fat tyre.
Knobbly rocky climbs are easier but smooth uphills are more of a drag. The wall climbing grip from the Nate tyres is almost comical at times, they are also fantastic on off camber slippy grassy stuff and wet roots.
The mukluk geometry is really sorted and is just a really fun trail bike. That's what it was bought for really. Being good in snow is just an added bonus really, I don't expect to do much snow riding tbh.
SSStu those chinese carbon rims you were interested in have arrived. They look good. I'm just waiting on spokes to build them onto mango Kings for the TB I'll let you know how I get on with them.