Just wonder if this is possible without losing any data and configuration.
Is there a selection of features that I want to install or do I have to install all features with ICS Premium?
It ist possible. I did it.
But if you would try it very safe - set up a new server with a fresh ICS installation and copy the "old" Registry-Informations and User-Folders from V.8 to the new ICS-machine.
Here is the KB-Article to move the user-Accounts: http://support.ipswitch.com/kb/IM-19980116-JB11.htm
Greetings Stefan