Maybe this perspective helps:
Is there any other media type that covers more than one document type (root element in the case of XML, but could also be non-XML mime types)?
It would be interesting to see how those (if any) deal with the issue. An example would maybe be iCalendar, Ithink.
Also: If feeds and entries get their own media types, then a feed (consisting essentially of a bunch of entry documents comes pretty close to a multipart/related message - which would make the very existence of the feed media type questionable.
And another thought: HTML has in a sense also two processing models within a single mime type (normal body and frames) and does not have a substantial problem with that, does it?
Jan
