The matias just costs half a grand more and can be used on linux as well as windows.
It is possible to achieve the same with a custom keyboard layout (see xkbcomp) on Linux.
I don't see the point of a half keyboard, unless you're somehow forced to use one. I've also tried it for a few weeks (using Autohotkey) and as BlackWidowMan777 said, it's going to significantly slow down your typing speed and double the strain on your typing hand. Maybe consider a DECT-headset and speech recognition software like Dragon Naturally Speaking instead.
PS: Just wanted to add that using Autohotkey or xkbcomp gives you the ability to modify the layout at any time, so you're not stuck with what the manufacturer came up with.
Agreed on all points and I might try the linux workaround, but also wanted to add there are some more alternatives to share the load away from the rigid typing stance so to speak:
1. iPad apps such as Penultimate and 7notesHD Prem allows hand writing recognition;
2. conventional pen and paper - 'experts' say that the physical act of writing gets the creative juices flowing much more so than the act of typing, which is mostly robotic and relies more on memory than thinking with both sides of the brain;
3. if your injury is arthritic in nature e.g. trigger finger due to ulnar deviation caused by iPad hand or the crappy traditional QWERTY layout, you can manage to type at full speed by say using ur left middle finger for 2,w,s,x effectively allowing you to use all your heavy actuation keyboards whilst totally resting the injured finger. Comparing this method to the matias half keyboard or the AHK script I can get up to 65 wpm and 97% accuracy. And that was just for the short time I had sprained my left ring finger;
4. hunt and peck (just don't let Linkbane/HellPirate catch you doing it on a mechanical cos he can fence and he is a prima dona of 10 fingering the keyboard in the fastest, lightest, and most efficient way possible.)
5.
http://www.lightio.com/ allows you to type without even touching a physical key using light beams;
6. that bracelet thingy that senses your typing by goodness knows how - but you can still use it on your mechs just with a feather-touch.