I do a lot of riding in the south metro down to about the Zumbro river and between the MN and MS rivers. I haven't found more than a handful of Minimum Maintenance roads, and they are only minimally rougher than the gravel ones. There is a road east of the MN river about 5 miles north of Le Sueur that actually has a couple of switchbacks. There are a lot of more fun roads and ATV trails in the Superior National Forest around Isabella and Finland. Also in the Chequamegon National Forest in northern WI.