This in10did device might actually ship, which beats vaporware hands down.
That's a pity, because a far better design was announced on Slashdot over a decade ago (http://hardware.slashdot.org/story/02/08/12/1413250/build-a-custom-fit-one-hand-keyboard) which still looks much more comfortable for heavy use (http://www.chordite.com/).
You need to change your basic premise: There is no possible way to prove that software is bug free. The best you can do is to test a piece of software and then fix the problems that you find. Software verification and validation are tough problems.
Touchscreens could just become the single biggest public safety hazard of the 21st century. The user instructions on all the ones I have read (including popular ones such as the iPad) expressly forbid cleaning them with any sort of liquid other than water.
People have dirty hands. Sometimes very dirty hands. I rather doubt that a little water on a lint-free rag is going to remove the huge smudgy colonies of bacteria and other things that collect on them.
There are all sorts of nice trackballs out there now. This wiki page from my favorite input device website might be of some interest: http://geekhack.org/showwiki.php?title=Island:10242
The CST LaserTRAC Trackball looks especially promising. You could replace the provided ball will a pool ball or a perfect sphere of any material, so long as it was the same size. This means you could try out heavier trackballs.
Apart from the users of 3D CAD packages like SolidEdge, most people have no knowledge of the nice 6-axis-of-rotation 3D input devices out there. 3Dconnexion jumps to mind as a good manufacturer, and they even have new drivers to open up the use to non-CAD users.
Every six months or so, I trawl the Internet looking for any new heads-up displays which add their signal to the one your eyes are already receiving instead of blocking out the world altogether and replacing it with some sort of display.
Are there any augmented reality HUDs out there? I've yet to see any good ones that you could walk around outside with while managing not to be mugged or hit by a bus.
If anyone ever commercializes the Chordite one-handed mobile keyboard, please wake me. It has been a hobbyist project for far too long.
Whether you prefer buckling springs in IBM Model M keyboards, ALPS keyswitches on a DELL AT101/AT102, or Cherry Blue keyswitches on any one of the tens of models out there, this thread is for you.