Hi Lucy,
I know this is an old post but thought I answer anyway.
I have had the opportunity to use MUS and Miquon. My dd6 prefers Miquon. I do not think MM and MUS are compatible.
Currently we are using Miquon and Life of Fred. My older son is using MUS but I’m not sure it suits dd as she really likes Cuisenaire rods and Miquon.