My views might not jive with others', but I think real Black is the way to go.
You have to clean them no matter what, so it's no big deal. Real Black has a significantly lower ignition temp so your less likely to have any hang/misfire issues.
I've shot most of the substitutes in the past but still find the real deal to work the best for me.
I ran the whole circle with ML's, started out with an inline just to be able to hunt an extry season, then went to a sidelock, then a sidelock and patched round ball's, then ditched the .22's and picked up a caplock .32 for squirrels, now it's a flintlock .32. It just never ends.
I apoligize for rambling, LOL. I like real Black Powder.