I really enjoyed this cocktail, although half way through I removed the ice chunk because it began to lose the complex rich flavors due to dilution. I saw this recipe on another site that uses 1/2oz Green Chartreuse so I split the difference and did about a 1/3oz. I love these cocktails that use 1/2oz or less of Green Chartreuse, because it blends with the other ingredients compared to dominating the flavor profile like in a Last Word, which I do enjoy but don't make often.
I've never tried Cherry Heering and don't want to add seldom used bottles to my blooming bar (many are on the ground and some in my bedroom). I've searched for substitutions and haven't seen Luxardo cherry syrup from the jar of cherries as a sub. I understand that it's non alcoholic so maybe that's why, but in a cocktail like The Simon where it calls for only 1/4oz Heering I'd be interested to know what people who've tried Heering & Luxardo syrup think.