Brenthoward...I would be very curious to know more about your uncontrolled study.
What supplements do you and your friends use? Do you follow a pre-load and post-load protocol? What are your ages? Are you all male? How great would you estimate your loss of empathy is?
I have been taking MDMA for the past 18 years. Never as extreme as you and your friends, but I had my nights where I took 5-6 pills instead of 2-3. My use was mostly limited to once a month (or once every 3 weeks if I was feeling especially eager). I never expected a significantly negative outcome, based on the research that I followed at the time. Now, my use has slowed to 2-3 times per year.
I would be very interested to know what your genetics are (especially your methylation mutations). If you are willing to run a 23 and me or Ancestry test, there are a lot of third party apps you can run the DNA through to glean more info.