Thanks for the responses folks!
I have my spare wheel for the Schwinn Speedster built up with the Bendix Yellow Band hub, which although I tore it down and built it back up with very light grease, has quite a bit of internal resistance when being driven, although not when freewheeling. I attribute this to the drag of the returder spring. (funny the forum auto-nanny won't let me spell it correctly) I read in another thread that they will free up with break-in, so perhaps this hub was never used much, or perhaps not at all, (it was an Ebay buy, of unknown provenance, but looks quite perfect) and isn't broken in. I also have a Bendix Red Band, which clearly has some miles on it, and that hub seems quite a bit freer.
I'll be on the lookout for an S2C. I can think of a few bikes that would benefit from a second ratio, but where I don't want additional complexity of cables. A 20" Royce Union folding bike comes to mind.