I experienced ego-death, in fact everything death, on high does ketamine (400mg insufflated, no tolerance). Basically all meaning and knowledge was erased. I didn't know I existed, that there were people, or things, didn't know that the world existed, or that there was even a thing called existence. I came out of what was probably a near anaesthetic state to what I now think was pure visual perception, a swirling chaos of raw, unparsed visual data. I didn't know it was perception, or that I was perceiving it. The entirety of the universe was a swirling void which, as far as I was concerned, was both me and everything.
Slowly very basic things returned, a sense that consciousness was continuous and persistent, so with it a very primitive sense of time, which recurred like a deja vu of a deja vu or a deja vu..., etc. The idea, or facility, came that I was experiencing what I perceived, and that such experience might be good or bad; some basic pain/pleasure instinct kicking in perhaps. Later the idea of life and death, that I was alive (though I had know idea of what I was) but wouldn't always be, that I had a lifespan.
Later still I became aware that there was a thing called people, and that I was one of them. Shortly after (perhaps, time was undone) that there was a normal world that I was not in, but did exist, but I didn't know where, or why I was not in it. My friends' names returned before my own. I think the return of the knowledge that I had taken a drug was the kick back to some sense of order and reality. Shortly after I realised I was in a physical space (my living room), and out of the k-hole.
Quite where my ego died and when it returned I'm not sure; the sense of self was a slow build from a primitive perceiving, through a thing that could separate that which perceives from that which is being perceived, to a sense of enduring one's own existence, then knowledge of oneself as one of many beings of the same type, etc.
Dangers? Even though the trip was not scary (or pleasurable, just neutral), afterwards I felt like I had taken a serious psychological beating, though a recoverable one. A week's derealisation and some hypnogogic flashbacks and back to baseline psychology after that, but I think that something profound has been learned, and some space created where the world is known as it was within the k-hole.