The single humbucker is what gives the MM it's punch. They are not overly bright or overly dark, lots of low mid thump and bark.
You mention that you don't hear a big difference between maple or rosewood boards. It is a little subtle, and is more like a final seasoning to compliment your playing style. I play mostly finger style and I like a warm sound without too much high end. Maple boards have a tiny bit more clackyness to them in comparison to rosewood. What technique do you employ most? If you slap, you will hear the ultra high end (or lack of it) pretty distinctly. Slappers tend to prefer a maple board. Another thing to keep in mind is that you can roll off existing treble much easier than trying to add it when it's not there to begin with.
Finally, do string differences pop out at you? With strings you have many gradations of brightness which can be used to temper a bright bass. Flatwounds are at one end of the spectrum and steel roundwounds are on the other. There are also lots of options in between.
Keep in mind most of these descriptions are generalizations, and there are always some exceptions.