I could never really see much difference in brightness between the P60, Scorpion, and the P90, although as Al mentioned, the P90 beam covers more area (larger filament + same reflector = broader beam). The P91 is somewhat brighter, and covers a LOT more area, but I am not a big fan of the high-current (P61/P91/N62) lamps. After melting a lens with a P91 I converted the light to a 9PT and was extremely satisfied. I now believe that the turbos are the best option for the 9 volt lights - at least as I use them.
-BCK