As an editor he is known best for editing works of P. G. Wodehouse and his involvement with their re-issue as paperbacks in the United States.
As an author, he is known best for his 1978 humorous alternate history novel, And Having Writ..., published first by Bobbs-Merrill company.
He was a consulting editor for Dell Books and The Dial Press from 1976 until 1981, and was instrumental in the establishment and acquisition of titles for the joint venture between the two imprints for their Quantum Science Fiction series, a prestigious international trade name that included such major works as Stardance by Spider and Jeanne Robinson, the seminal story collection The Persistence of Vision by John Varley, In the Ocean of Night by Gregory Benford and The Snow Queen by Joan D. Vinge.
He also contributed editorially to Dell's paperback science fiction and fantasy publications during those years.
Bensen was a member of the all-male literary banqueting club the Trap Door Spiders, which served as the basis of Isaac Asimov's fictional group of mystery solvers the Black Widowers.