Every "split" mechanical keyboard currently being sold that I know of

split_keyboards.md

• Kinesis Freestyle (Terrible key switches. Mushy and un-lovable)

• Kinesis Freestyle Edge (Traditional layout with too many keys, mech switches, proably too big to be tented easily/properly)

• Matias Ergo Pro (Looks pretty great. Have not tried.)

• ErgoDox Kit (Currently, my everyday keyboard. Can buy pre-assembled on eBay.)

• ErgoDox EZ (Prolly the best option for most people.)

• Diverge 3 (Looks great. Might buy one. Ergo-dox really has too many thumb keys anyway. This might be a better design.)

• Diverge TM 2 (Cool idea. Magnets! Too few keys for me.)

• Keyboardio (Halves can optionally be separated. Looks promising, but too few keys)

• Dygma Raise (Nice thumb keys layout, but no arrow keys and probably too big/unweildy for effective tenting)

• UltraErgo (Does not appear to be mechanical)

• Ultimate Hacking Keyboard (Small layout, mech switches, intersting-looking thumb attachments but missing arrow keys! And Kinda ungly)

• Lets Split (Dunno what this is yet)

• Mistel Barocco (no arrow keys, but looks good if you like 60% keyboards)

• Goldtouch (Technically one-piece, but close enough. I've used these. They're crap.)

• Goldtouch Go (Technically one-piece, but close enough. These are also crap.)

• Comfort Keyboard Split Magic Keyboard (This looks terrible)

• SafeType Keyboard (Also looks terrible)

• Axios (Something gloriously weird that is under development. Maybe.)

• Cheap Split PCB Boards for sale (Totally DIY. Soldering required!)

How long did it take you to get used to the ortholinear key layout on the ErgoDox?

I've got a Matias Ergo Pro. It is pretty nice, but in over a year of use I've got several sticky keys. I have other non split mechanical keyboards from steel series so I know there are better switches out there. Plus the keyboard is missing some important keys. Like insert for example.

You're missing a couple good ones:
https://gaming.kinesis-ergo.com/fsedge/ - Kinese Freestyle Edge - Freestyle 2 w/ mechanical keys and programmable layers
https://ultimatehackingkeyboard.com - programmable mechanical

This one looks interesting too: https://www.indiegogo.com/projects/dygma-raise-world-s-most-advanced-gaming-keyboard#/

Keeb.io makes a few different PCB's for splits

Kinesis Advantage, Kinesis Maxim Combo and Maltron dual-handed might count.

Freestyle Pro was released by Kinesis recently: https://www.kinesis-ergo.com/shop/freestyle-pro/.

It looks very similar to Freestyle Edge, but is a bit cheaper, and comes with no wrist rests.

Maybe this one? https://www.amazon.com/Koolertron-Programmable-Mechanical-Keyboard-Ergonomic/dp/B076FTKD6F/

Don't waste your time with the Matias Ergo Pros ... they are wonderful hardware with HORRIBLE firmware. I've owned 4 of them and every one has had different firmware issues from ghosting to phantom keypresses to caps lock lights randomly coming on (and staying on even when caps lock is not engaged), etc. I just sent back 2 of the new "soft touch" ones. The keys themselves are great, if they can ever get their firmware issues sorted out.

this one is pretty cheap and beautiful, not sure about the quality though.
https://item.taobao.com/item.htm?spm=a230r.1.14.29.68d16222La6Gri&id=556970472669&ns=1&abbucket=4#detail

Thanks for this list! This is out of stock but this is exactly what I'm looking for:

https://keeb.io/collections/frontpage/products/quefrency-60-split-staggered-keyboard?variant=12204552880222

A whole family of wireless splits I worked on https://github.com/joric/bluetosis (see end of README). Split keyboards are generally bad, your old typing habits become pretty much nil and you need different muscle memory for every possible distance between keyboard halves.

been using matias ergo pro for about a year now (avg ~3 days a week) and i definitely have a number of keys that are ghosting/jammed up. i don't recommend it.

Thanks for the good list. Are there any non-split ergo mechanical keyboards? If not, is there some physical limitation as to why that can't be? Thanks.