There was an interesting article in this months issue of "The Arilleryman" (Vol28, No2).
They did not include "Skirmish Powder" in the test unfortunatly, but they did Goex Cannon-F-2F-3F, Elephant Cannon, Lidu Cannon-F-2F, Swiss 2F, Schuetzen 2F, Pyrodex RS, and Black Canyon. All were evaluated in a 12 pound mortar for power, consistancy, cost per pound, cost per "distance".
Goex brand came out on top overall out of the ones tested.
Great magazine by the way !