John,
As a person that was born and raised in Lake of the Woods County I read the previous post with great interest. Although I no longer live in the area, I think the post pretty much nailed my hometown area from my perspective. I suspect that this mystery area is close to home. To paraphase Sarah Palin, I could see Canada from my high school classrooms. Heck, we only had Canadian TV when I was in high school. Every time we heard "Oh Canada" we stood up out of habit.
One of the problems (as is evidenced from the many posts) is the difficulty in defining "Northern Minnesota". Some people think of Brainerd or Fergus Falls as northern Minnesota. Sorry, this is not northern Minnesota. Most people from the northern part of the state divide the state into three regions, all of which are north of Duluth: Northeastern Minnesota, Northern Minnesota, and Northwestern Minnesota. The distinction is important because the riding conditions are dramatically different.
I just got back from riding in the L.O.W. area and I can tell you that in the woods where the wind isn't a factor they have an honest 30" of loose powder. This year is the exception rather than the rule but it is sure fun when it happens. As far as the trails are concerned, we rode for three days and encountered four snowmobiles that weren't part of our group.
As to why people don't ride in this area, there are many reasons but one common thread is that it's rugged. Some of the point-to-point rides are over 100 miles and there is nothing in between. Thankfully, the local clubs do an excellent job of providing shelters every 20 - 50 miles so you can build a fire and warm up. If you're looking for bars or food every 20 minutes, it isn't the place to ride.
Regarding snowfall, sometimes less is better. the trails don't mogul up and with the lack of melting, 8 - 12" of snow will support the trails for a long time. I've ridden in the Arrowhead county and really enjoyed it but I could see where grooming might be an issue with the heavier traffic from the metro area. In my hometown area I've actually met more groomers than snowmobiles on some rides.
I've ridden the U.P. for many years and my daughter lives there so I'm also a fan of the Michigan experience but thanks for posing the question. Remember, you didn't hear any of this from me.