Yes, that's an interesting article that's been referenced here in past years, for example
here in discussing forward vs down-firing subs. The author's points about the advantages of corner placement of a single sub seem very solid, but his suggestion about placing two subs along the front wall is a bit shakier. Although he correctly points out that the room mode in that one horizontal direction would be cancelled, other positions aren't discussed which involve placement at nulls and opposite phase points, e.g. the midwall front and back, or mid side walls, or diagonally opposite corners, which are among the best positions measured in the Harman paper.
