Personally I very much prefer this in the same style as a whiskey smash - which is to say, with double the agave syrup and half a lime, cut into quarters in the shaker. The tequila and mint honestly need the acidity to balance things out.
Ballantine's Finest, Tia Maria and Angostura cocoa bitters, along with what little syrup stuck to my bar spoon after lifting the cherry out of the jar - earthy and fairly dry in a way that highlights the common ground between the scotch, coffee and chocolate, but with just enough sweetness to round them out. Lovely!