At first, I felt this was missing some sweetness and mouthfeel. But, after downing it in 3 sips, I can see its appeal. The orange and cognac flavors are still bright and vibrant on my palate minutes after the last sip.
This might be of very niche interest, but since you mention the drink's origins being murky... The drink is mostly noted as coming from the 1946 Stork Club Bar Book, but it actually goes much further back. Non-alcoholic Egg Sours appear in some very early bar guides like O.H. Byron's. But as far as I can tell this version that includes brandy and Curacao dates at least from the 1888 Police Gazette bar guide. And it's very nice!