Slightly straying from topic, but asking for opinions more than anything.
Would you put Zappa in the category of prog, or do you consider him (as I do) to be BEYOND prog? I think Yes, Rush, Floyd when I hear the label "prog". Zappa was so far off the beaten path I always thought he WAS a category.
Zappa was a self-taught traditional composer whose primary creative outlet was writing orchestral music he would never hear on sheets of music paper, from when he was a kid to the day he died. The whole rock n' roll thing was a money-making sideshow for him, and he relished holding his audiences in contempt – though he did grudgingly accept the respect of the classical community in the end.
He is absolutely in a class by himself.