I went from a Kinesis Freestyle 2 that I'd used for almost a decade to the Glove 80 with the Glorious Engrammer key layout/functions: (https://sunaku.github.io/moergo-glove80-keyboard.html#layers)
It took a few weeks to get used to, but now that I've got the muscle memory down it's a blast to use. Having function layers makes so much sense once you get used to them. Why use Control + C and Control + V and the hand cortortion it causes on a daily basis when you can hold down the G letter key and then press j/k to copy/paste. The thumb cluster is quite handy as well, I have one button mapped to a custom script that I run dozens of times a day.
Who holds his hands as shown in the image in the article?
I own two Glove80s, but for me the ultimate split keyboard with a thumb cluster was the Dygma Defy, of which I now own a pair as well. Couldn't recommend it enough. https://dygma.com/pages/defy
The designers were extra mindful of different thumb lengths, making it so that you can usually find a configuration that feels natural and not cramp up your joints: https://dygma.com/blogs/product-development/how-we-developed...