got the same problems as you, KDE is not the problem (neither GNOME is), problem is the lack of documentation for developing plugins.
I'm currently trying to replace win installations with Outlook in an Exchange network where users heavily rely on exchange benefits: email, contacts, meetings, schedules, tasks and so on.
If you're looking for a complete exchange access (email confirm meetings, shared contacts or agendas, shared mail boxes, ...) I think even OpenChange or other solutions are quite far from original Exchange/Outlook pair

Did you try Thunderbird email client?
That works great on Linux (KDE or Gnome) or windows clients;

brother.. change to GNOME to get best performance