Duplicating to the same directory is my most common use case. However there's always scope for both, ie adding the second version to shift-apple-D.
The dialog at least has the decency to remember where you were last time, so if you're
repeatedly saving files to the same directory, be it the one the original file is in or another
one, it will do the right thing with minimal hassle. I suppose that's part of the reason I'm a
bit resistant to forcing a particular directory: if you don't, it will usually go to the right place
anyway, whatever "right" happens to mean for you. *shrug*
If I remember correctly then --with-file will only work when --with-directory is specifed.
No, --with-file works on its own. I just tried.
Robin