As far as Spiritual Unity and Ayler in general is concerned; it's a matter of how open-minded and receptive you are to the different forms of jazz. To me, Spiritual Unity is just as essential as Kind of Blue or the Hot 5's and 7's. I'm not a big fusion fan, but if someone said that Bitches Brew should be considered a "cornerstone" in a well-rounded, jazz library, I couldn't disagree. Same with Spiritual Unity IMO.