Lotta thoughtless trolling in here from those who don't own or operate DH devices.
As a consumer electronics design/mfg guy by trade, I'll be the first to say that the DH is a manufacturer's nightmare, ugly, bulky, and that some of the macro-ergonomics of it could be improved per the other notes here -- tenting angle, bulk, cables, etc.
But it IS effective at relieving RSI symptoms while still enabling efficient typing.
Some weirdly baseless stuff being thrown around in this thread.
I've got three, have been using DH for 15 years, and it literally makes me able to work.
I *super* wish I could use something else simply because it would make my life a little simpler, cheaper, and I wouldn't live in fear of HW failures, but all this talk about lateral finger motion causing tendonitis in the upper arm and elbow... I've never experienced that.
There are many problems with DH (lack of usable mouse is #1, so I use a renaissance mouse in between the units, not ideal but oh well), but the basic ergonomics are fantastic and worth some study for folks looking to learn and move industry forward. Learning curve is high, but if you spend $1k on a keyboard, you are in a different class of motivated user anyway. If learning curve were the main thing keeping it from being adopted, nobody would use Dvorak either.
Price killed it. DH is just plain expensive to build. Go look at the dodo-hand to see how hard it has been to reproduce.
In any case, glad to see that its memory lives on, and happy to contribute to any thread where someone would like input from an actual long term user.