This one's a keeper. I agree it could either benefit from a dash more lime OR pulling back on the syrup a smidge. Really bored with this Denizen Merchant's Reserve (in cocktails), but it's more than serviceable here along with my new friend, Pusser's Gunpowder.
Personally find it needs just a little more lime to achieve the bite I want from a daiquiri, though I appreciate how this really shows the rum. I added an extra ~½cl which did the trick for me. Also used a demerara syrup which seems logical for a dark daiquiri
It's definitely my own ingredients which make it flawed, but somehow, the dark rum overpowered the aged rum. So unfortunate, because I'm sure when made with better ingredients, it would be great.