0xDECAFBAD has a very nice example of RSS 2.0 and RSS-Data alongside.

If you use schemas with RSS, you get eveything that RSS-Data provides and more to the point, you make the data structure definitions optional.

The only downside as far as I can see is that with RSS-Data the structural definitions are inline.

Surely, however, since schemas are in XML themselves they can be inline - rather like CSS being inline or referenced?