If you introduce that feature please make it optional. I love the idea of typing novels to get a more intense connection to the content. Gameification for WPM would disrupt this. Please consider this use case even though I understand that this ist not your target audience.
Absolutely it will be optional. The intention behind the site is as much to support author's works as it is to practice typing. I originally figured that having it update more often than once a page might be distracting, which explains why it works the way it does now.
