I cut firewood (standing or recently fallen dead wood) by hand with a bow saw for 6 years (25-30 cords total) when I was living in Garrett Co., MD. It was great exercise and lots of fun for me, but then I enjoy dumpster diving for aluminum cans, so... Anyway, with a bow saw, one has to cut smaller diameter wood (<8 inches) because cutting larger wood burns you out too quickly.
Based upon cutting smaller-diameter trees where I lived, hickory (Carya sp.), hop hornbeam (Ostrya virginiana), musclewood (Carpinus caroliniana), and black locust (Robinia pseudoacacia) were the hardest wood I encountered. Some of these species are not found in the UP. Young sugar maples were about as easy to cut as oak. This matches with wood hardness data for these species as well. However, a gust of wind tore off a large limb from a huge hollow sugar maple (>3' diameter) next to my camp that crushed the pavilion next to the house. That limb was a B!TCH to cut up with a bow saw, and the portion of the hollow tree trunk that tore off with it was easier to break up with a sledgehammer rather than try to cut it up with a saw. It burned and smelled great, though!
So, in my experience, sugar maples can be very, very hard if they're old, large trees. Sugar maple is probably the hardest flooring material up there. Do you have any products from old timber raised from Lake Superior, Deering? The grain is beautiful! I considered doing that for a living at one time many years ago. There's very valuable wood from old timber drives on the bottom of lakes all across the upper midwest and Canada.
I hope you're still cutting and heating with wood. "He who cuts his own wood is twice warmed."
