Ctrl-[ is impossible to type on, say, a German layout, as the [ character is hidden behind AltGr + 8, where AltGr is the right Alt key, which is itself (for most terminals/systems) just the combination of Ctrl+(left)Alt. So you'd basically have to type Ctrl+(Ctrl+Alt)+8 which is not possible....
I remember reading something, or maybe it was a talk on some conference, by someone who had some deep knowledge of the terminal layer. He explained some ways for alternatives to, say, ctrl+i, because something about the way the control characters only use 5 bits and if you type ctrl + a key that has the same lower 5 bits as "i", that also works like ctrl-i or something. I've been trying to find that video (or web page) again but I couldn't. But I think back then I found a replacement for ctrl+[ but I have long since forgotten it ...
Also, swap Ctrl and Caps Lock:
setxkbmap us -option compose:menu -option compose:rwin -option ctrl:swapcapsAnd I understand that accidentally hitting capslock can also be annoying when typing, but that happens so rarely (for me) that it's not an issue, and one could always just disable the capslock key in that case.
What am I missing?
In the very rare cases where you need to change the indentation of a line, there's == or, if that doesn't work, you can indent a line forth and back with >> and << .