I created a file that uses ImportXML to pull prices from a set of web pages, and bless me, it works! To stay updated with the changes in price, I ticked the "Automatically republish when changes are made" box, clicked "Start Publishing," and selected RSS (as a list) as the output. Then I subscribed to the feed in Google Reader.
Without making further changes, the RSS feed spit out the contents of each row as a separate item. That's the only output that's been republished. I've made other changes to the document, and ImportXML has pulled in price changes, but nothing shows up in the feed. Sheets seems not to see these as changes.
I created 4 other files with the same setup but different data and found the same result: changes, but no updates.
Is there something about the republishing that I don't understand? Does it only examine the first cell in a column? Are there other restrictions I haven't discovered? I even turned on the Notification Rules and have gotten no emails from that source either. I'm at a loss.