We have just completed the preliminary study but I cannot publish any results yet. And you are right, of course. It does not help everyone. That's the way it is. But there is a lot of feedback thanking us and hoping that it will be available to as many services as possible.

I don't doubt that this will help people. I know how it helped me to train myself in the way I read today during my university years.

So as said - there will be people who benefit from this. Still - being an empiricist I just like to see independent and scientifically valid representative studies being done before I believe marketing claims. ;-)

I don't have links to studies but last time I checked and from anecdotal experience reading speed with high comprehension is limited by information throughput in the brain. It's also why languages spoken faster carry less information per word, because the limit is information processing. To experience that if you are a good reader, you can try to speak out loud a sentence while memorizing a second sentence and see that you'll not have process and understand the words until you have spoken them, even if you have read and stored them (short sentences like in TFA, obviously doesn't work on HN).