A friend of mine gave me a bottle of Domain de Canton French ginger liqueur. I tried this recipe using that instead of Grand Marnier. Highly recommended.
I love Benedictine, but this one comes out a bit too thick and sweet for my taste. I added another quarter ounce of sweet vermouth and loved the result.
It's been my observation that anytime a recipe calls for Benedictine, you'll get better results if you cut the amount of recommended Benedictine in half. YMMV