The inner voice and mind's eye don't surprise me, I'm among the more hyperlexic people I know and seem to have total aphantasia, but I didn't realize (though I guess it seems like an obvious possibility in retrospect) that there were people who processed words as text in their head - I guess the survey itself said that surprised them too.
I also didn't consider that there could be a large degree of variability in representational manipulation, and assume that this kind of inevitably leads to some pretty hard to bridge inferential gaps when speaking across that divide. Honestly maybe I'm misunderstanding what's meant by that, because the other extreme sounds to me like there are some people who just can't do metacognition which sounds insane. I'm guessing however that this is similar to an experience I had with a (now ex-)lover who was shocked when I mentioned I don't have visualization, and asked "So you're telling me you have no imagination at all?", which like, I wouldn't say is true? My imagination can be prosaic, narrative, auditory, abstract, olfactory, emotional, or kinematic, just not visual. I kind of assume that's similar to what I'm doing here, like whatever "manipulating representations" means here is a useful capability by which to do metacognition but not the thing itself... but it seemed like their questions pertained to a lot of different kinds of manipulation of abstractions or mental models, so I can't really figure out how you'd examine your thoughts per se without that ability. Maybe there's someone more knowledgeable about this field here that could help me understand the distinction?