While interesting, this document it's nothing more than preaching to the choir. My community and I recognize all of these features as being wonderful (except if you're a Macintosh user), and some of them have likely extended the life span of GroupWise here at my campus, but they are greatly overshadowed now by other shortcomings.
There isn't a single Macintosh user that would take the Mac GW Client, and the features on the list that do work, over something modern and well integrated as Mac Outlook. It makes me sad to say that, but it's the absolute truth.
If you want to keep customers, fix/address the reasons why we are leaving.
Let's see something from you on the Macintosh front...
Is there a new client on the way?
Is CalDAV and CardDAV in the works?
Moving from GroupWise isn't free, but when your customers are willing to spend the money, and accept the loss of some "coveted features," it's time to think different.