I agree with Bill Kearney's continuing rant about bloated full-content RSS feeds. If you include the full content for each item, then every time a new item is added to the feed the content of every item already in the feed is effectively downloaded again. Of course this may not matter if you have plenty of spare bandwidth. But for some of us it might make a difference to our bandwidth costs.
I've written about this before but I'd like to see the raw content of each item accessible individually so that the aggregator need only load the content once. The RSS file would contain a link to the raw content in addition to the link to the full page containing the item. I don't know enough about the RSS schema to know if this is currently supported. I've not heard of any aggregators supporting a feature like this.