I know you question really isn't about ergonomics and RSI, but I can't help myself.
I usually get pain in my little fingers after typing a lot. Switch to Dvorak has really helped, but I still had some trouble with typing "special characters". Using shift and cmd put a lot of strain on my left little finger.
What has been a huge boon for me is using pedals for the shift modifier keys. So to hold down shift I press down my right foot. That way I let my little fingers rest a bit and I have to use one finger less for key combinations.
It took me maybe a week to get back to (almost) my normal typing speed. And for me typing speed isn't the limiting factor when programming, it's my brain.
I also use the Advantage2 keyboard, note how the keyboard is "hollowed out". This means that my fingers can rest comfortably and not "bend backwards". Also note that modifier keys are placed by the thumbs.
So to sum up:
- Dvorak
- Advantage2 [https://kinesis-ergo.com/shop/advantage2/]
- Advantage Triple Pedal [https://kinesis-ergo.com/shop/advantage-triple-pedal-refurbi...]