> It is not a good idea to use the backslash as the trigger key since it is the traditional line continuation and escape character on UNIX.

Well it is also the default key binding for VIM's leader key and placed on the home row on US keyboards which makes it really accessible.

What is not shown in the demo screencast is that leader detects whether the cursor is inside a quoted string and in that case doesn't present a menu but tells the shell to insert a literal backspace at the current cursor position.

For continuing lines on an interactive shell the user would have to press Ctrl+V followed by a backslash to insert a literal backslash. In my experience this is rarely necessary in an interactive terminal so the extra utility gained by having leader on the home row outweighs the extra key press necessary for continuing a line.

> Furthermore it is not a good idea to replace the command line with a menu since that limits what is possible in UNIX.

That is true. Leader is not _replacing_ the command line, the command line still works as usual, the only difference is that you can launch a menu by typing backslash to quickly run a command.