[…] the old zarafa client had an online mode that basically worked as a terminal for whatever was stored on the server, KOE/activesync requires all data to be downloaded to the local client first.
This was absolutely great about the old client. It was possible to have a 100GB shared Mailbox for all users that was easily accessible within the office (remote access was not so great) without the need for every single client machine to have a 100GB local copy of the shared mails. Now with Kopano/Activesync every single client PC will store a local copy of those 100GB, which will then also increase the backup storage needed for each of those clients from 30GB (normal Windows Installation) to 130GB (Win10+Mails).
And now if there are synchronsation problems you have to trigger a full resync of the 100GB. Not looking forward to doing this
Summary: everything was better in the old days
(ok, not everything. Mobile use in Outlook with activesync is soooo much better than the old zarafa cached mode)