I started at 350 and that's still what I use most of the time. For light, non-technical articles, I can do 450, but it's a bit uncomfortable to focus that hard and I do miss things occasionally. I can usually tell if it was important or not though, so I know if I need to go pause and rewind. After playing with speedreeding off and on for a few years, I've come to the conclusion that it's definitely possible to read faster than I normally do with equal comprehension, but that there really is a limit and the claims you see from speedreading courses are hyperbolic. The thing I like about Squirt is that it eliminates the need to use a pacer.