I don't know where they fall but I've had some terrible trips.
I thought about being shoved into an oven, and dying in an ambulance afterwards.
I've gotten terribly depressed and almost incapable of moving. I'm not sure if it's depersonalization and/or derealization but some of these trips have been total disasters.
I've had thoughts that I'm dead/dying/in hell. It's weird and terrible. Edit: I'm not sure the trips would have qualified as Cotard's Syndrome, but I don't think so.
I've had so many trips like that... I just assumed it was part of the "dissociaitve trip", is that you might some times feel like you're going to die or about to die. Or you could have horrible physical side effects the entire time, which just exacerbate your anxiety or whatever.
And then there's the fact that DXM is very dirty, you're basically overdosing on an SNRI to get the dissociative effects. And it's metabolism can vary so wildly, that you can have so many different trips on it. And many of them can be on the frightening scary side.
I look at it like this, psychedelics show you reality warped & beautiful colors & patterns, but DXM just takes you to an empty black void, almost like it's giving you a taste of death.
Near death experiences & out of body type of experiences are not actually that uncommon on DXM. It's just that they don't always happen every time & some people might get lucky & avoid some of them at all depending on how often they dose, what they've eaten, other factors, etc..
I found smoking too much weed on the peak of a DXM trip definitely made it worse, like just complete loss of touch with reality, dark, omniscient freaky feeling.
And then I could have trips where I just vibed & listened to the music the whole time & was fine, so.. lol