Just made this cocktail twice - once with Dolin Dry and once with Martini & Rossi Ambrato. There is an ENORMOUS difference in favor of the (slightly) sweeter amber vermouth. I'm not sure from where the suggestion to switch to a dry vermouth came, but it's a mistake in my opinion. With the Ambrato this is, indeed, an amber Martini with a subtle sweetness and lovely finish. I used Tanqueray, Angostura Orange bitters and the aforementioned M&R along with the St. Germain.