More than a month after my commitment to the default built-in completion system I can say that everything has been going smoothly. I adjusted my muscle memory to hit TAB in the minibuffer whenever I need to pop up the *Completions* window, which to my surprise has not been happening as much as I was expecting. The only thing that I added to the original setup is the following:

(keymap-set completion-list-mode-map "M-e" #'switch-to-minibuffer)

This is easier to reach than M-g M-c when I want to move from the completion window to the minibuffer. Admittedly, it’s not something that I do often, but it can be useful if I need to edit what I have just typed.

If you are wondering why I chose M-e for this, the answer is simple. I like isearch-edit-string and use it regularly, plus the e in M-e reminds me of the verb “edit”, which is what this key binding allows me to do.