[dTal]

>The benefits largely come from the trip itself, rather than the trip being a side-effect

Well, that hasn't really been scientifically established, has it? It could simply be an illusion - just because I had a transcendental experience, then I woke up the next day feeling amazing, doesn't necessarily mean the transcendental experience caused me to feel amazing. No doubt there is some truth to it, as people report all kinds of life-affirming revelations that persist when sober, but we shouldn't exclude the possibility of psilocybin as a therapeutic drug in the traditional mould.

An experiment I would like to see is whether the positive after-effects of a macrodose are still measurable if the subject is unconscious the entire time. Helpfully, this would also blind the study, although a possible confounding factor is that medically rendering someone unconscious has after-effects of its own.