I spent the better part of two days working on why the site's feed was working only intermittently. I discovered the problem when Entrecard wasn't showing the most recent posts. So, today, I removed all references to FeedBurner. Now the site is strictly standard WordPress feeds. The types of feeds that wouldn't validate without huge changes, I simply don't offer.
It's very common that something will work and work and then suddenly stop without any indication. Turn a plugin on or off, and another one or two can malfunction.
Well, the site is much lighter now. That's fine. I don't think people were particularly enamored with the bells and whistles anyway. It isn't as if they were being used much. I don't think those bells and whistles will be missed.
I'm also glad that I don't have to make the migration from FeedBurner to Google, who bought FeedBurner. I'd read about many of the problems seasoned bloggers have had with it, so that's another pain I won't have to endure.