Eric Tecosky's original recipe for this cocktail calls for 1.25oz of Jack Daniel's Single Barrel instead of the combination of Tennessee and rye whiskies...
This was considerably sweeter than I was expecting (or really like). Adding .5oz fresh lemon juice--essentially turning it into a Paper Plane with Pamplemousse--made it quite lovely, though, for me. (The beauty of cocktails, right? One can adapt it to one's own palate, always...)