From the start, I was concerned that this was going to be too sweet. Both Cointreau and green Chartreuse are sweet. With the addition of the rich syrup I was concerned about the sweetness level. Made it as posted and yes, for my palate, it was way too sweet. Even with the salt rim. Made a second one without the rich syrup and it was definitely more balanced and the Cointreau and Chartreuse flavors were more prominent. My advice, unless you like overly sweet cocktails, leave out the rich syrup.
Honestly I feel like the salt did this a disservice. It muted the bracing quality of the chartreuse and triple sec, and rounded out the lime a bit too much. While it could be that I filled it too much and mixed in a bit of the salted rim, I'll try it without salt next time.