I wonder if there is some sort of ergonomic benchmark for IDEs or keyboard shortcut layouts.

What I have in mind is given some representative code sample, how many keystrokes are needed to perform a set of common tasks like duplicate line, reverse the order of function arguments, etc. There could be penalties for uncomfortable shortcuts like CTRL-B on QWERTY.

I definitely think the mac OS cmd based keystrokes are much more ergonomic than the windows ctrl based keystrokes. For windows you have to hit ctrl with your weak pinky, then awkardly stretch your index finger to somewhere on the keyboard. It's an awkard movement that I don't think my hand otherwise ever makes during my life. It seems like a recipe for strain to me, doing something not commonly done by the hand regularly. I think it originally was expected that users would use their other hand to type right ctrl since there wasn't a mouse back then, but these days everyone keeps their right hand hovering the mouse or trackpad rather than hovering over the home row.

With cmd based keyboard shortcuts, your hand basically forms the default resting limp hand position, with your thumb on the cmd button, and your index finger lazily and easily finding the other key to complete the shortcut. Your thumb is basically always there anyway due to the spacebar. It's a much more natural movement.

Using two hands for key combinations is step one to avoiding RSI.

If you need to keep your hands on the mouse (for example, CAD or video editing) then get a keyboard with programmable macro keys, or a separate macro pad.

For example, a Kinesis Freestyle Pro, or a Koolertron.

In the long run, your limiting factor is how much your favorite keyboard layout fucks up your wrist tendons by making them rub against the inside of the bones of your wrist (the “tunnel” of “carpal tunnel syndrome”).

Indeed. Stenographers regularly hit 200wpm on chorded keyboards, with a record of 375. We haven't adopted that tech en mass because speed isn't the only factor