I used Evolution for a while and while it did have some really nice
features, the thing that bugged me was that it took forever to switch
from Email to Calendar, and that simple things like coloring a certain
email blue when it came in would never work.
I just read a file by ConocoPhillips submitted by a European field
office. They were trying out Evolution and they concluded overall that
it slowed up productivity.
Well, if anyone knows of a solid Outlook replacement please let me know.