Welcome Internet neighbor.
The Emacs community commonly suggests mapping the left Control key to Caps Lock to avoid RSI. I suppose we can all agree that on a standard keyboard, the real estate value of the Caps Lock key is higher than the function it covers — if we ignore the minority that prefers to type "all caps". However, the popular Ctrl-on-Caps solution will cause long-term harm1.
One of the first things that is taught in a touch typing class is to use a modifier key with one hand and the key with the other. For example, the exclamation point ! should be typed by pressing the Shift key with the right hand and the 1 key with the left.
Having a left Ctrl key right beside the A key is more comfortable than reaching the bottom left corner of the keyboard. This works well when chording2 with keys covered by the right hand. The problem is the implicit suggestion that the left Ctrl in its new position should also be used for the keys covered by the left hand, stretching the pinky and index finger to reach the furthest keys. That movement will create hand problems in the long term. In my experience, lateral finger movements are the most stressful when typing.
My advice would be to extend what's suggested: put the left Ctrl in place of the Caps Lock, but also put the right Ctrl in place of the Enter key. Let's forget for a moment that now we lack a key to enter commands3. To use Emacs with reasonable comfort, one should use a symmetrical keyboard, with pairs of modifiers of generous dimensions in sane locations. That disqualifies the majority of off-the-shelf computer keyboards. What remains is not a big selection — anyone is free to pick their poison: Kinesis Advantage, TECK, Maltron, Ergodox and a few other less known custom keyboards.
And no, before someone suggests Vi mode: I'm not interested in that debate.
The inquisitive reader would point out that notebooks with similar keyboards don't exist. My answer would be to pair it with a symmetrical keyboard again. In my opinion, the comfort of modern notebook keyboards is appalling, with their short key travel resulting from the race to create the slimmest device. By the way, to my horror I've seen desktop low-profile chiclet keyboards too.
Anyway, I know that traveling with a keyboard, even if compact, kills the usefulness of a notebook. For those situations, I've found a better approach:
On my notebook I remapped the Spacebar as a dual role key: when pressed and released it will insert a space, but when pressed with another key it will act as a Ctrl modifier. This works with the touch typing principle because thumbs are neutral and can chord with either hand. It's not perfect as I lose the space repetitions, but who is still indenting code manually in this day and age? For browsing, I can use the Page Down key (unfortunately hard to reach on my notebook)4.
It's a combination of xcape and xmodmap, this is the code I've copied from xcape's author:
# Creating a spare modifier
spare_modifier="Hyper_L"
xmodmap -e "keycode 65 = $spare_modifier"
xmodmap -e "remove mod4 = $spare_modifier" # hyper_l is mod4 by default
xmodmap -e "add Control = $spare_modifier"
# Map space to an unused keycode (to keep it around for xcape to use).
xmodmap -e "keycode any = space"
# Finally use xcape to cause the space bar to generate a space when tapped.
xcape -t 175 -e "$spare_modifier=space;Control_L=Escape;Shift_L=parenleft;Shift_R=parenright" > /dev/null
Note that I also have a left Ctrl that's a dual role key with Esc and that the two Shift are dual role keys with open and closing parenthesis respectively (useful for Lisp and Emacs Lisp, where parentheses dominate).
This unconventional setup works better than it sounds, and even with all its problems I don't miss the TECK when I use my notebook.
Unfortunately xcape doesn't work on Wayland, so I've started to write something similar for it, but I'm not in a rush because Emacs doesn't run natively on it.
To summarize: symmetrical keyboards with dual modifiers are ideal for Emacs, but when mobility matters, dual role keys offer a reasonable compromise that respects proper typing ergonomics.
Yes, I'm aware "Considered Harmful" is itself considered harmful in computer science literature. At the date of writing, Google Scholar reports over one thousand results with this phrase in the title. Ironically, none titled "Considered Harmful Considered Harmful". ↩
the process of pressing a modifier key and a normal key to type a different character, like a musical instrument chord ↩
on a terminal I habitually use Ctrl-m instead of Enter ↩
damn you Dell, would have cost too much having two more keys? ↩