I've never shot anything but real BP in my traditional muzzleloaders. I do have a scoped unmentionable, that I've never shot anything but Pyrodex pellets out of. I haven't taken it out of the closet in 4 years and will probably sell it soon. But, other than smelling like a skunks butthole, I got excellent accuracy out of Pyrodex pellets, zero ignition issues, and it was no more time consuming to clean than real BP.
That said, I could buy a pound of 2f 777 just to see how it runs in my perc Hawken, but why? If it was relatively easy for you to get real BP, would you still buy 777? It's no cheaper, I find it even pricier than Swiss BP.