The orange bitters are key to balancing and adding depth to the equal parts aged rum and sweet vermouth. However, go easy with those dashes or bitter orange...
Used Ron del Barrilito and Cocchi. This was as complex as advertised, and less sweet than I had anticipated. Nice to have a Manhattan variation that's a little lower ABV and more tropical in the mix.
Nice and complex but need to try it with a different rum. Used a 5-year column rum (The Navigator) and it was bullied by the vermouth. Orange bitters and zest brings it together.