I think the purpose of Dasher and the other input techniques mentioned is to be able to quickly enter text in constrained situations, whether its due to size restrictions of the device or due to limitations on the input vehicle (e.g. single finger, one handed, thumbs only, etc). I think in any of these situations, I would be more then happy to be able to enter input as fast as I could type on a standard keyboard.

Now if someone could invent a faster then keyboard text entry system that had a decent learning curve, I would be all in. I tried Dvorak and never was able to type faster then on Qwerty, plus it took way too long to adapt too