I tryed some a few weeks ago, and had some high expectitions, but it had a noticable delay in my flintlock. I did not try, to add any black powder to it. It did good in my caplock and Ruger Old Army, however, it seemed like it had less power. I did not get to chronograph it, so I'm only guessing.
I agree, if I have to add black powder to it, then I might as well use black powder.
Even with what seemed like less power,it did shoot very well, and I shoot some nice groups with it.
However, lower power loads, are often the most accurate loads, anyway. It cleaned up easy, and you can shoot all day without any build-up in the bore, or at least the amount that I shot.
I give it a high grade for target shooting,(in caplock), but would need more testing, before using it as a hunting load. It might be great out of a flintlock with 5 grains of black added,but I haven't had the time to get to the range to test it.