I recall that with Merlin Messaging 2.5 and Magix 2.2 and up, the user would now see the number of new and saved messages on the LCD display. Also, the mail seems to pickup much quicker when you dial 770. Must less of a pause. I think beginning with R2 you could increase to a max of 12 ports up from a max of 6 ports on 1 and 1.1.
Beginning with R3, I believe the user activity menu is expanded with additional options beyond 8 for answer mode. I think pressing 9 listed of another menu of additional features.
As stated earlier, you do pickup the delay announcement feature for calling groups in the later releases as well. Hope this helps.