If you have a pocket of wet wood in the middle, it will disappear fast if the fire in the stove is already hot. The idea is to mix your fire with really dry wood with some that may not be that dry. That's why I sell mixed hardwoods. Dry elm, ash, and maple will burn anything that might be moist -- oak, for instance. Oh, and don't forget poplar and cottonwood.I am surprised Whitespider hasn't dropped in here.
As you stated, a cheap MM is not going to give you 100 percent accurate counts for any species but it gives you a great idea of how your splits are doing relative to where they started. And I have found that "feel" can mislead a person sometimes. I had some ash that clanked when whacked across itself but when you split it there is still a visible pocket of wet wood in the middle.