Sorry to be a wet blanket, but Magit for Emacs already has a convenient UI for reviewing diffs (as well as viewing status, logs, rebasing, etc.), so I don't kno

Sorry to be a wet blanket, but Magit for Emacs already has a convenient UI for reviewing diffs (as well as viewing status, logs, rebasing, etc.), so I don't know if I personally would use this tool from Emacs. But it wouldn't hurt to have an option to make "e" to open files in Emacs or the user's choice of editor.