That being said tho, the Wii composite output looks decent on composite (I've moved to component, but the composite isn't hideous...)
The Wii is mostly simple cartoon graphics, but I would say it is pretty bad. Component is far superior, except it shows just how blocky the graphics are.
S-Video isn't necessarily better than standard Composite video when connecting two devices. It depends on which device has the better comb filter. The signal is exactly the same before chroma and luma are split.
S-video was created purely to skip the step of combining and separating.
I can't think of any reason why you'd have something that would generate the chroma and luma. combine them to composite and then stick them through a filter to extract the chroma and luma. If you get a better picture using composite than using svideo, then either your equipment sounds broken or your definition of better is different to everyone else's.
Of course if your equipment can really only output composite, then you have the choice of letting your TV split the signal or put in a box that splits it and feeds it to the TV. But it's possible the DCTV does have points on the board you can tap the pre mixed chroma and luma.
