@G_Chem Since you like other products...you can go ahead and send that sexy magic to me and my partner... :D
This is what my partner and I experienced for years together. This was why we rolled. Although we both had individual histories with the drug prior to getting together, once we hooked up, ecstasy just became profoundly sexual in the best way possible. Interestingly, neither of us had ever had sex on ecstasy before we were together. It never went there with other people we were with. I had a few party cuddle puddle/making out type experiences, but nothing like what we found together.
That's why it was so disappointing when the product changed. It did not just take away the ecstasy experience, it took away a bonding experience that we valued together.
In any case...
@G_Chem, I agree with everything you said. I think it is likely a multi-faceted issue. We already know that different synthesis routes produce different impurities. Those impurities could increase, decrease, or alter the experience. This could be occurring due to interaction in the liver or the brain. As a result, different batches vary. Then, due to individual genetic makeup, mutations, overall drug experience, tolerance, serotonin system restructuring etc, each batch hits each individual in a unique way. There are also the set/setting factors like when you last ate etc.
Despite all of this, and believing that it is a complicated issue with complicated answers, I do think that someone will eventually be able to identify certain impurities that seem to decrease the intensity of the experience. I believe the only path there is lab testing. Although, reading the recent research with the M-Alpha HMCA impurity, it became clear just how insanely complex that lab work would be. It is not easy to identify unknown compounds, even with scientists in the lab.
I'm going to continue to test various products, take notes, and try to get lab data as often as possible. If the problem is not me, then I will happen upon the magic that I prefer eventually.