Indeed, the set and setting impact the details of the experience (as I've read). But there are also some universal features at the phenomenological level. Structurally, these experiences are similar in challenging conventions, undermining the ego, rewiring the brain, acting as existential therapy, and so on.

I also think they have devastating implications in the case of religion. If the foundations of religious experiences are psychedelic, that's quite the blow to theism, as I see it.