The orange makes all the difference - I tried it once with just lemon, and again later following the recipe more closely, and the citrus mix was far nicer and more flavorful than the one with just lemon.
Agreed! I've just tried to be sure as the original recipe states "Pone dash of Orange Juice" meaning small or tiny, but I have an equal-sized dash to the lemon. Perhaps 10ml lemon and 5ml or less orange?