And you could combine the Stopped Diapason 16' with the Dulciana 8' as a Dulciana helper to give you a "Contra Dulciana" at 16' pitch on the pedal. Very useful. The organ in one of my churches (2m H&H, ex RSCM) has a double stopped rank on the Great and, when combined with the Dulciana, sounds totally like an open rank, right down to bottom C.