Because of the silly way iTunes works the only way to update the URL for a feed is by setting up a permanent redirect from the old feed to the new. This seems easy, but I've hit a snag.
The old URL ended in /?feed=rss2, the new URL is just a file, so it ends in podcast.xml. When I redirected from the old URL to the new, iTunes picked up the new URL BUT, WITH the query string, so now the URL ends in podcast.xml?feed=rss2. This is allowing listers to download the show - which is good, but causing some other problems. Is there any possible way to set up a permanent redirect that will redired podcast.xml?feed=rss2 to just podcast.xml? Mod_Rewrite seems to just pass through query strings, so I'm at a loss!