Over the past year, I have dedicated hundreds of hours towards improving my reading speed. I usually use Acceleread on my iPad; most recently I used it to read D.H Lawrence's Sons & Lovers at around 750-800 wpm. I also use Beeline -a different type of reading tool with some additional functionality for dyslexics- when reading web pages.
I've learned that certain types of prose make for poor speed reading material. Without a "rewind" option, there is no way that I can use these apps to read anything instructional or anything involving a high level of detail (such as a mystery novel). I understand that allowing the user to rewind would sacrifice speed, but speed can't always take precedence over clarity.
Also - in terms of the text- there needs to be a better method for handling quoted text. With speed reading apps that give the user the option of seeing chunks of words, it is far too easy to lose track of who is speaking when one chunk of words has an opening quotation mark and the next chunk of words [may or may not] have a closing quotation mark. I'm guessing that this problem is exacerbated by the fact that - in Spritz's case- words are only presented one at a time.
Here are some things I would I would like to see adopted by speed-readers:
Rewind functionality
Punctuation-based text color:
If the text is in between quotation marks, parenthesis or brackets, this text should be shaded a slightly different color than the rest.
Contextual deceleration:
I would love it if a speed reading app would automatically slow down at the end of a chapter. The last few sentences of a chapter are usually crafted with especially deliberate care and are meant to be savored.
More customization options for dyslexics:
For example, Beeline allows users to chose a specific type of font that is specifically geared towards dyslexics. In the future, I'd like to see speed readers enable these types of fonts (as well as customization options for line height and letter spacing).