So the plague of the S1000's appears to be the direct drive. Since I don't own one, I can't go look at it closely to see how its all put together. However, it would seem that with the right parts, it could be converted to a freewheeling chain drive. Naturally, "the right parts" could be any number of customized things, but for this purpose I was thinking of stock or readily available parts.
Looking at TheSuperKids, http://www.thesuperkids.com/scchgemali.html, there appears to be a sprocket, drive gear, and chain, readily available. The trick is probably how to get the drive gear on the wheel, right?
I may be picking up a used and broken S1000 very soon, and thus why I am interested in this. I can't leave anything alone, and I'm sure it'd get the 1000W motor at 48 volts rather quickly. So, the chain drive would be the way to go.