In revisiting this cocktail, I found I like bumping up the rum to 1.75 oz or 2 oz - it helps temper the sweetness of the pineapple with a stronger rum presence, and actually brings out more of the amaretto flavour.
This cocktail also benefits from more age on the rum, such that El Dorado 8 or 12 year work much better than 5.
This cocktail also benefits from more age on the rum, such that El Dorado 8 or 12 year work much better than 5.