> The presentation of the words is also centered rather than aligned, which requires a saccade for each word, which defeats the whole point.

Does it actually require a saccade?

Testing with a quick and dirty command line RSVP program I have, my speed and comprehension seem about the same with either centered or left aligned. But I'm mostly testing with fiction written for the average adult. The words are usually short enough that they are within the field of good visual acuity no matter where withing them the focus is.

I've not done a comparison using text with a lot of long word.