This eye gaze solution has really shined where the off-the-shelf system we had before didn't. Although, to be honest, probably the biggest hurdle to using the eye gaze in a meaningful way is building all of the pages, which pretty much amounts to defining a language. It took a lot of time and effort to build that out, but the rewards have been huge. Since SquareVoice is free (as opposed to paying thousands of dollars for a license of something else), it's been a lot easier to put it on more than one computer. I recently put together a third device for my daughter that fits on her wheelchair. The setup has a much smaller screen, but is lightweight and truly portable. Time will tell how well this form factor will work.
I've got to say, it's incredible to now have access to off-the-shelf inexpensive eye gaze hardware that really works well. And also to have a plethora of tablets and ultrabooks on the market that are powerful, have integrated touchscreens, and work great with the eye gaze hardware. Not counting mounting hardware, I think you could build a decent eye gaze system for about $600 if you went with "refurbished" hardware.