I was worried that EmEditor did not support two-keystroke keyboard shortcuts like Emacs does, but now I know that the User Menu option will allow two-keystroke shortcuts.

My suggestion is to enhance the User Menus by allowing an extra modifier to the shortcut. For example,

C-x C-s Save
C-x s Save All

If I set User Menu 2 to C-x, I want to be able to choose C-s for Save, and just 's' for Save All. I understand that currently, there is no way to differentiate between 's' and C-s, but this would be a needed enhancement for people who are already used to emacs.

One suggestion is to have a different modifier for Ctrl.
Save (^s)
Or perhaps one for Alt also:
Save All (%s)
Or perhaps also case-sensitive:
Save and Close (&S)

Thank you for your time.