Isn't that pretty dramatic? Do you think you're a better than average case because you also wrote the program?

The Supermemo technique should be good at keeping the pace up to get to that magic 6000 character level. Once you get a lot more data I would think you would have something worth publishing in journals of education and that could be a very nice PR opportunity for you, showing that your software dramatically improves the time needed to become fluent in Chinese.