Your idea about sentences does affect the experience, but I don’t believe that makes it worse; it’s just a different approach. Once a whole sentence appears on screen, your eyes move across it again, so the no eye movement part is lost. What remains is the return sweep, the long jump back to the start of the next line, and the moment when you lose your place on a dense page. Those are real challenges in normal reading, and chunking by sentence removes both. You would end up closer to guided pacing than RSVP, which might suit a book better anyway.
Let me know how the procrastinated book turns out.