I made with 15ml rich (2:1) cinnamon syrup (roughly equivalent to the 22.5ml (1:1) cinnamon syrup in the recipe). Cinnamon integrates really well in the cocktail and the 65ml of 40% liquor is also dangerously hidden. I remade with all the ingredients cut back by a third to retain proportions while adding sobriety and making better fit an old-fashioned glass: 40ml blanco tequila, 10ml triple sec, 20ml grapefruit juice, 10ml lime juice, 10ml cinnamon syrup, 4 drops grapefruit bitters, 20ml soda.