Cozee, I was skeptical about MM at first. I finally got some and BOY does it make a difference. Trust me on this, I'm a cheap miserly ol ba#@$^ and wouldn't buy it if it didn't work. That, and you can do dozens of pens with the SAME 2X2" pieces so long as you always wet sand and don't heat it up much (I also rarely use it directly on wood, only the finish, which sorta makes me a black sheep around here).
It's got a lot more consistency in the grain pattern, and the 12,000 grade is actually about as fine as a 6,000 to 8,000 grit sandpaper.
My final step on CA and acrylics is 12,000 and then I use 3M's Finesse-It II polishing compound, using a scrap of automotive leather as the applicator. Insane polish.