Well, if MUS is truly working for you and the kids like it, I wouldn't switch.
To answer your first question, though, yes they do. Even my eldest who is a words and language guy all the way "gets" it. I, who decidedly didn't "get" it growing up, now get it.
My youngest, who enjoys math, is a perfect whiz. She doesn't have it all memorized (yet) but she does complex stuff in her head and gets the right answer.
Hope that helps.
Susan