JIMW I agree with you. While earlier versions had some desired features that Mail did not, the latest version is bloated with 'features' that may not be wanted, unstable, and missing desirable features, that were present in earlier versions. That is why I have switched back to Mail even though I own Entourage.
Additionally I have found an undocumented feature in Mail that is not present in Entourage. When Time Machine backs up Entourage, it backs up the entire database each time with all the mail buried in the database that is backed up. When Time Machine backs up Mail it backs it up logically as separate mail messages, even it it is backing up the entire database each. This means that each mail message is searchable in Time Machine and can be retrieved as such. This is a valuable tool in a situation where you have deleted a message but find out later you need it. Simply enter the approximate title or sender of the message into Time Machine and retrieve the deleted message. While this product might be helpful in this regard for Entourage, it is probably not as convenient, and given Entourage's other issues, especially it's printing capability for its Calendar, I will continue to use Mail and ICal thank you.
(Version 1.4.1)