We have started training. So far there has not been an uprising but there has been a lot of grumbling about the lack of these features.
Bug 7257 - Support read receipts and delivery reports in webmail Bug 22014 - Recall message from Outlook/ZWC. Bug 7524 - Delayed delivery of mail
We're hopeful that we'll win people over the first time they do a search or tag a message but people tend to remember when you're taking a feature away even if everything else is better.
Are you still seeing appointment duplication? We still have it in build 2095 and the bug is showing as still open.