I'm not what you would term a spyderco fanatic. *sounds of boos*
Of the items I have handled, I tend to prefer those made by that OTHER company (*cough*benchmade*cough*), though I admit that Spyderco stuff is certainly just as good, and from what I've seen/heard, Spydie's QC is better.
However, I know what makes a spyderco a spyderco to me...it is the humpbacked blade. Obviously, this stems from the hole. However, it is not JUST the hole. The AFCK sports a hole, and could NEVER be mistaken for a spyderco. Sure, some spydercos do not sport 'hunchback' blades, and to me they do not look like 'real' spydercos.
One way or the other, its not the clip. Everyone has them. Its not serrations. Again, common. Hole? Naw... its the unique blade profile that comes from the hole, IMO.
In a side note, be aware that I'm buying a Rescue 98 sometime in the future, so there is hope for me yet. And my wife says Spydercos 'look pretty'...
Mike