Among other things, AmphetaDesk lacked a liberal RSS parser, RSS auto-discovery and support for item-level dates, all of which can be found within Syndirella. Syndirella’s best feature, however, has to be the built-in scraper which allows you to syndicate sites which refuse to provide an RSS feed. I have successfully configured several HTML-only feeds for syndication in this manner.
These features come at a price, however, as Syndirella requires the Microsoft .NET framework, a 20MB download. Still, even with its bugs it’s probably the best Windows-based news aggregator out there.