I love my serrated Delica. I cut a lot of cardboard at my two jobs, and I find that the serrated edge is better than the straight edge for that task. I plan on picking up a straight edged version soon though for those more mundane chores.
I recently traveled to San Francisco, and another attractive feature of the Delica is that I was able to pass through security checks at both Minneapolis and San Francisco International Airports without any funny looks when I put my knife in the basket before passing through the metal detectors. I don't think I would have been able to do the same thing with my AFCK.
Speaking of the AFCK, I cut cardboard with both the AFCK and my Delica today, and wouldn't you know it, the Delica actually performed better. Damn you Spyderco, I could have spent that money from the AFCK on two more Delicas. It carries lighter, and definately attract less attention and instills less fear than my AFCK. Don't get me wrong, if I anticipated needing a folder for defense (not that I'd bring a knife to a knife fight - I'd bring a rifle, or go to a knife fight at all) I'd definately take the AFCK, but in a politically correct climate like the one I work in, the Delica is better to have handy.