I just got the UKPK and love it. I look forward to the Urban. The 2.5" blade will allow me to lawfully carry the knife in the federal building where I work, provided I grind 1mm or so off.
18 U.S.C. Sec. 930(g)(2) excludes "a pocket knife with a blade of less then 2 1/2 inches in length" from the definition of "dangerous weapon."
Of course, if Spyderco would like to make the Urban so that it can be lawfully carried in a federal facility without alteration, it would sure make some federal employees -- not to mention others who go into federal buildings -- very happy. How about 2.4"?
Note: the 930(g)(2) exclusion does not create a "right" to carry a < 2.5" blade into a federal building. Rather, it means you won't be breaking the law if you do. Rules vary from facility to facility.