Who's to say that even a single dose of MDMA is even harmless 35-40 years down the track?
Many toxins do not poison you directly. Some like asbestos and Beryllium compounds take 30-40 years to cause their damage, the outcomes always proving fatal in both cases. We don't yet know what MDMA will do that far down the line because the longest anyone has been taking it is probably only now approaching 30 years.
While it's unlikely MDMA will prove to be such a toxin, there are many unknowns with the drug. MDMA would never have got approval if it had been entered into clinical trials. The points outlined above demonstrate this, as although a drug having one or two of those side effect may be approved, a drug affecting 4 metabolic processess in the way MDMA does, would not.
Heroin as mentioned, does not cause any neural degeneration. Apart from its very toxic result from actions on the central nervous system, heroin is remarkedly non-toxic to organs. During addiction, the body even learns to produce various endogenous chemicals from the metabolism of heroin.
A few of my old hometown friends have died of heroin overdoses, others survived only to feed their addictions. Yet others - and that's most of my mates who've used H- are still alive, happy and healthy. A couple from the old crew probably still use everyday, but both have always been very strict about dosages. Once driven by necessity to secure themselves a lifetime supply, neither is tempted to go silly apart from the very occasional social "splash".
I've also known a few users who held very important jobs, and afaik none were ever suspected or accused of being users. I hated the effects of heroin myself, having smoked it on a couple of occasions. But just because I find MDMA used occasionally to be preferable, it doesn't mean I see it as being less dangerous pharmacologically speaking, apart from the obvious difference in respective margins for dosage error.
In the end, weighing up the good and possible bad, particularly when talking about some of the recent "research chems", it could be said the
safest option may be to go with the devil you know
Used regularly, I agree with middle finger. Heroin, like most drugs, has the potential to reduce the spark. It's all to do with the devils (self induced manifestations etc) who also "move in" with any addiction.