Dasher: Writing text really fast without typing or speaking

This would be awesome for people who are disabled. Voice input is still a pain and only works with a limited number of applications. If you could somehow switch between keyboard and tracking for the mouse pointer, this could give full use of a computer to many people.

The android keyboard version of Dasher is available in the F-droid repo: https://f-droid.org/app/dasher.android

This is really awesome. It looks hard, but it isn't. Here's a talk from 2007 that explains it well https://www.youtube.com/watch?v=wpOxbesRNBc

Wow, this looks really cool. Looks like something you could do while exercising, like with a stationary bike or treadmill.

Appears to be really hard to pull off. How many hours of training does a person need to achieve let's say 20wpm?