RSS feeds update
It looks like the problem might be a syntax error in the RSS XML feed: A space that appears at the very beginning of the feed.* This would account for why some readers (like mine) work and some don't; some are more finicky about proper syntax than others.
Unfortunately, finding out where the space comes from seems to demand the manual examination of hundreds of PHP files.
So to avoid that I'm going to have to be clever, and that's a big problem.
NOTE This is a neat data point supporting Goldfarb's Law:
If there's a problem in a text processing system, it involves whitespace.
The first character of the feed ought to be the opening character of a sequence that will define the character set used in the document. So when the RSS parser (or at least a finicky RSS parser) encounters a character (a space, but could be any character) before knowing what character set it comes from, it barfs, and so it should. Sigh.