My history with keyboards started as a senior in college when my wrists started to hurt. I decided then and there that I would spend my career using properly ergonomic keyboards, which meant split columnar. My first was in 2002, a FingerWorks TouchStream. That was an amazing gesture-touch input device which was excellent for everything except typing.
For typing, you really want the tactile feedback of buttons so after a few years I replaced the FingerWorks with a Truly Ergonomic Keyboard which I really loved. This was during the period when do-it-yourself keyboard community was coming together, and when new formats became more common starting with the venerable ErgoDox. I switched to an EZ, wrote a custom four-layer layout for myself, and came to really appreciate that design. I've used it for over a decade now.
Recently the folks at TEK sent me their new Cleave keyboard to review. I spent time using it and I'll compare it to the ErgoDox and to the original TEK.
The Cleave ships with high end infrared mechanical keyswitches. Instead of making an electrical contact at the bottom of the keystroke, the mechanism interrupts an infrared LED to actuate the keystroke. They claim these will last longer but for me the takeaway is that the sensation of producing a button press is very smooth and consistent. I never miss a letter by slightly underpressing the key. They feel great. They are tactile keyswitches which is what most people prefer, although myself I prefer linear. The keyswitches can be swapped out easily but most people won't bother because these are very good.
A keyboard should sit heavily and steadily on a desk so the baseplate is important. This one is stiff and heavy, made of aluminum. It feels nice, it is heavier and sturdier than my ErgoDox EZ. The whole thing feels right, you can pick it up without flexing, it can clunk down without worry.
Some keyboard nerds like unmarked keycaps because that's elite, but I like keycaps marked with their glyphs. Some people point out that unmarked caps can be remapped without mismatching the cap marking, but my retort is that keyboards only need to be mapped once and then used forever. I'm not rearranging the base layer of my keyboard very often, or ever.
The Cleave has nice cylindrical keycaps, either OEM or DCS or similar shape. The glyph font is nice and the shint-through is pretty. The sound they produce is satisfying, a light click on my version.
My main ErgoDox is the original unlit version. I also own the underlit Shine version and the backlit Glow version but I don't use them because the lighting is unsatisfying. I don't care for underlit at all, and the EZ Shine's backlighting is weak, mushy-colored, and doesn't cover the whole board. I think the folks selling the EZ were aiming for the gamer boi l33t h4x0r RGB crowd.
By contrast, the Cleave's backlighting seems to be targeted at professionals who want an attractive useful keyboard used often in low light. That's me. The lights are clear white, not mushy, they don't flash, and they'll never impress middle schoolers. 10/10
I use qwerty layout which is preset on the Cleave. Many ErgoDox users remap to a different layout but not me, I set up mine with as ordinary of a layout as possible on the main layers. Each of these keyboards has an appropriate columnar-staggered layout; that means the letter button placements on both keyboards are equal.
The Cleave has a dedicated Escape key in the proper location: separate from the other rows of keys, up to the left in the corner. That is where Escape belongs and the Cleave has it but the ErgoDox doesn't.
On the other hand, the Cleave puts arrow and nav keys in little clusters underneath the letter buttons whereas the ErgoDox has another row of buttons. I use the ErgoDox buttons for Command, Option, Hyper, Meh, and Control. The Cleave lacks all of these and instead has two buttons for Control and Option on the far outside bottom corners under the Shift key. There are configuration options to move Command onto the caps lock key, or one of the spacebars, which a lot of people like.
Proper ergo keyboards move more functionality from pinky to thumb. Both Cleave and ErgoDox do this but the Dox does it a little better. The Cleave has basically two buttons per thumb but the Dox has quite a few depending on how far you reach; I commonly use my thumb for all three lower buttons in the thumb cluster plus three more of the command buttons.
But let me say one thing, which is that the Cleave has nice wide horizontal space bars, like they should be. ErgoDox really requires you to hit an exact spot for the space bar and it took adjustment not required by the Cleave.
Both keyboards are split into left hand and right hand sections but the Cleave is on a single board whereas the ErgoDox is divided into two parts. Most people are comforted by a single unit keyboard but I've found over a decade of use my hands have drifted farther and farther apart, now at the maximum allowed by the connector cable. In my opinion, having a split-not-divided board like the Cleave robs users of the opportunity to evolve their typing toward greater comfort.
I'm not aware of deep firmware customizability on the Cleave. If it has it, it's not QMK which is the nerd's choice for keyboard firmware. My ErgoDox has not only a custom layout but some of the layer setup has custom C code. Almost all users won't do that but I did and you can't do it on a Cleave.
The reasons that I won't be giving up my ErgoDox are not reasons most keyboard users share: I want divided left and right with more thumb buttons and customizable firmware. My willingness to use unusual keyboards is already greater than the audience served by the Cleave, which is an audience I used to be in and to whom I would recommend the Cleave. People more like me can look at an ErgoDox or Iris. As for me, if I give up my ErgoDox it will likely be for something like a Manuform.