Well, I purchased a double wall and I'm glad I did. Hot tea made at home with boiling water took about 10 min to cool to drinkable temps, i.e. not lip scalding hot, the rim was only warm to the touch and the tea stayed hot while leisurely drinking it. Cold beverages seem to stay cold as well; ice lasts a while in the cup and the outside didn't sweat. Not really a backpackers concern I know, but a concern for someone like me who will use it for everyday use.