You could certainly use those powders but you will not get any different velocity than you would out of any other muzzleloader. Smokeless MLers get the velocity they do due to the powder not anything unique about the design.
I agree if you use the same amount of Black Powder you will get the same results out of any gun. I just thought SP barrels could handle more preasure than a common BP barrel. If they could I was wondering if you could use more BP i.e. 200 grains instead of just 150 grains