You can map any key to any position easily using a simple GUI, including making hardware key layers. And, since the firmware is open source, you can modify it to do anything you want. Many of the hardware components can also be altered/replaced by equivalent parts.
Unlike other keyboards, like the Lexmark M15 and Cherry G80-5000, where the only action performable by the thumbs is punching the spacebar, ErgoDox has extra keys placed near the spacebar, within thumb reach. This prevents the thumbs from being a bit redundant.
Because of its split design, the ErgoDox lets you optimize the positioning of its halves according to what's best for your body shape, even if you have broad shoulders and large hands.
This can be fun, but some people just want a working keyboard without having to spend three hours with a soldering iron. It's tricky to find pre-assembled ErgoDoxes, and they're not mass-produced. It is also possible to commission an enthusiast to build one up as well. Some Massdrops of the ErgoDox kit did came with an option allowing one to choose whether to have it pre-made or not.
As the Ergodox is an open source design, you'll either get each component individually or purchase it from Massdrop. Either way, it's not possible to return if you don't like it.
You can attach trackpoint, trackball, trackpad and additional key clusters to the board. This allows for extensive feature customization, for increased productivity and convenience.
The UHK has a split design, since two keyboard halves result in a more natural typing posture. The halves are connected by a bridge cable, which expands and contracts as needed, occupying minimal desk space. The halves can be merged together as one, which is useful for transportation purposes or if you happen to prefer a one-piece keyboard.
For maximum touch-typing productivity, one's hands should not leave the home row frequently. With conventional keyboards, this is not the case when navigation and function keys need to be used. On the HKB, via a thumb key press, several function layers can be activated, turning the home row keys into function keys.
The UHK is modular and has disassembly instructions embossed onto components and even printed on the circuit board. It records use data, so when key switches have reached the end of its lifespan, users can replace them.
The height of the middle section is adjustable. The two halves can be angled up to 15 degrees so that your hands can stay at a comfortable, natural angle while typing.
This keyboard folds in half, which is nice, since it makes it conveniently smaller for transportation. Since it folds inwards, the keys are protected from external elements.