After spending more time with SharpReader, I have a few more comments/suggestions:

• My earlier request for setting default refresh is apparently built in (although not obvious to me until Luke told me how to do it): Click on the root folder in the tree and set the refresh for the folder. This will then propagate to the children.
• It would be nice if the systray tooltip told me when there were new posts available. Or maybe the icon could change.
• It would be nice to have a way to "Delete Posts Older Than..." It has a Delete All method, but to use the threading I think you have to have the old message.
• It would be nice if I could post from here.

That's it for now. This is a very nice little aggregator.