I am bumping this thread to say that I just picked up one of these yesterday. I have about 60 of these wonderful CDs, but I had never seen this before:
IT IS ESSENTIAL!!! I am blasting it through my headphones now, and it sounds so tight and intuitive. It's supposedly early modern creative music (according to the allmusic.com review), but I think it's completely accessible and structured, so don't worry.
I don't know if this is a super rare one or not, but just like the Valdo Williams and Charles Moffet ones, you should check it out!