I definitely fall into the "to each his own" category. I do own an ornamental sgian dubh similiar to this (lousy image) that I'll wear with my PC... if I deem the circumstances are appropriate. For instance: I wore it at my wedding, but not at the Governor's Inaugural Ball (where security would likely have looked askance at it).

However, as I generally don't carry a knife when un-kilted, I don't see any particular reason why I need to carry a knife while wearing a kilt.