I wonder if you can combine this with Vim so that you could use it for lightning fast cursor movement and selections and still use the keyboard for anything else.
The trackers he listed have an accuracy of about 0.3-0.5 degree which at a distance of 50cm to the screen still maps to a fairly large area of about 50x50 pixel (depending on screen resolution and PPI). That's far too big to guess where you want your cursor to be placed.
Moreover, the fact that you'll see the cursor moving creates a loop in which you will follow the delayed cursor around with your gaze.