Personally I think that the S&S was the wise choice and much more in keeping with the bespoke image that Morgan invokes. With an H-D the focus probably would have been on the "Harley engined trike" rather than the "Morgan Three Wheeler" . Also I heard at the factory that H-D were just too demanding in their requirements.
As far as the Cush drive is concerned, I've seen the interior and the grease (!) and now that the cars are out with the public I just can't see why there should still be any secrecy.