Does this work for anybody? I've plugged in 3 feeds, one was "unable to retrieve full-text content" (an sfgate.com feed) and the other two returned nothing at all in the preview (one a feed from kqed.org, the other an older wordpress blog).
Funny, I just added sfgate too and it worked for me: fulltextrssfeed.com/www.sfgate.com/rss/feeds/news.xml
I have a lot of experience with fetching and parsing feeds and pages, so I'm not trivializing the problem, just observing issues I'm seeing with this solution.