In addition to your thoughts above, I’d also highly recommend people take a look at Rapid Serial Visual Presentation (RSVP) technology which is primarily headed by Spritz (though there are a multitude of knock-offs on the market). The basic premise is that the technology helps to prevent subvocalization while also simultaneously getting rid of seccadic eye movements. I don’t find it as useful for technical reading, but magazine articles, newspapers, and most fiction work well with this method. I’ve written a bit about it here: http:/
Based on psychology research for plateauing, one can continually increase one’s speed by pushing one’s limit up several hundred wpm and then backing off a bit, which will make the speed seem slower than just prior, but still faster than previous bests. I’m sure there’s some upper hard limit, but I now find reading at 800+wpm very comfortable without losing comprehension significantly.