Lou,
I would absolutely buy an S scale set if it was done as faithfully as you did the NH 209 set in O scale. With your commitment to quality and accuracy in making reproductions, a good repoduction set with the older style heavyweights in green or red would very, very nice, IMO, especially if it had reproduction boxes!!!
I may be in the minority here, but I would also be interested in one of the early link pin hudson passenger sets like the: 4613 or one of the old 332 passenger sets like the: 4617.