Very nice post and thanks for the shout out.
I discovered Devilman while watching Yasuhiro Imagawa's Shin Mazinger (Another excellent highly recommended Nagai adaptation) and in it, some people were pointing out that it had references to some Devilman manga panels. I was intrigued and decided to check it out.
I read it in one day was left stunned by its content. This manga came out in 1972!? Wow, it's pretty much not what I was expecting at all. Many who read it nowadays may not find it all that shocking, but I can only imagine a manga audience back then who were only consuming your average shounen manga by the likes of Shotaro Ishinomori and Ikki Kajiwara (Both amazing authors by the way) and stumbling upon this stuff.