Thanks very much for the nice words, they are much appreciated.
I think that there are pain receptors AND heat receptors involved. In my limited experience, there is always a balance of heat vs pain in the Superhots. This one had huge amounts of heat AND pain. The Madballz 7 I ate was far more pain than heat, although it was extremely hot. I thought the Reaper had far more heat than pain. I will do some research and try to find out the science behind this.
One thing I have noticed is that the ones that generate more pain give you a much more pronounced high afterwards. After the Madballz 7 I was very mellow and laid back for 30-45 minutes. After this cross it lasted 90-120 minutes and was much more intense. I was very high and spacey indeed. The high was quite similar to low dose fentanyl I had for an operation on my back. I went though an awful lot of heat and pain to get there, though, plus I had some stomach issues for 4 hours or so. No cramps at all, but my stomach was sore.