I read this at 800 wpm (adjust this down @ 10-20% if a test I did a while back still stands) fairly comfortably using http://www.spreeder.com/app.php. I find it very much easier to stay "in the zone" using it.
Yeah I should probably add, I've only used it intermittently. For whatever reason I don't find it comfortable enough to replace regular reading. It works best for articles and the like where I want to actively extract information or quickly ascertain quality.
Seems like those problems could be corrected by slowing down on the problematic words.