I want more flexibility in the appcast classes so my delegate can make changes.

As a delegate of the SUUpdater 
When I implement updater:didFinishLoaadingAppcast: 
Then I want to be able to reject items from the app cast items collection based on app specific criteria.

I am aware that I could implement bestValidUpdateInAppcast:forUpdater:.  But the problem with that is that it completely replaces the BasicDriver's selection functions.  I like those and don't want to recode them.  It might be nice if my delegate could call the default behavior, then make it's own changes.  In general I think the AppCast and AppCastItems should be more open to modification by the delegates.  It would be nicer if the values in the items were properties I could change.