This is a nice, tasty cocktail, simple to make.
As the quantity is quite small overall I have doubled the amount of gin which makes the drink still balanced given the Benedictine BOM is quite sweet.
I also use Noilly Prat, and I have now made this both with and without 5ml of sugar as recommended by another comment. I can recommend this addition if using Noilly Prat. (I also flame my garnish; the lemon really adds something to the nose.)
This is the cocktail that has brought me the most compliments. It reminds me a bit of tea with honey, which I attribute to the Benedictine combined with the lemon twist. As someone else mentions in the comments, this is a drink where the twist plays an essential role.
This recipe seems to date back to 'Old Waldorf Bar Days' (1931). There's a similar drink - albeit with orange bitters - called the Ford Cocktail in Kappeler's 1895 'Modern American Drinks'.
Having only a bottle of B&B on hand, I bumped the ratio to equal parts hoping to balance things out. The drink was perfectly balanced with a very nice herbal complexity. 9/10
As the quantity is quite small overall I have doubled the amount of gin which makes the drink still balanced given the Benedictine BOM is quite sweet.