Where I think the argument starts to break down is by lumping all reading into a single category. Reading a novel for pleasure, and wading through forty pages of background information before you get to the five crucial ones, are fundamentally different activities. I'm a medical student, and the majority of my reading consists of that second type. You can't really "digest" a literature review in a way that makes it enjoyable. The only real goal is to get through it once, without getting bogged down.
Regarding the pauses, that's actually the area I put the most work into. It lingers three times longer at the end of sentences and twice as long at commas, specifically because a consistent, flat pace feels like reading a script rather than actual prose. And, of course, you can pause whenever you feel the need; there's no pressure to keep moving forward.
The part I'd really push back on is who this is actually for. The people who've given me the most in-depth feedback today are clearly avid readers. It's not really a tool for people who don't read much.
Reading a couple of books weekly, and switching between these reading styles, also makes me think the reading speed should be set per book, not as a general setting. If you're reading Tolkien at 250 words per minute and a fast-paced paperback at 450, you shouldn't have to adjust the speed every time you pick up a different title. Since it already tracks where you are in each book, remembering the reading speed for each one seems like a logical next step.
Anyway, that's a really helpful point.