Rodwhaincamo,
You are wise, it would indeed be foolish to imply real BP has ignition problems. I have not seen the claim from Black MZ from the source, I only read what was posted by DR1445, ie, in the quote it seems to imply that it solves ignition and cleaning problems experienced with traditional BP.
If I was incorrect, I happily stand corrected.
I guess I have seen this question come up many times for both percussion and flintlock, and based on my experience with subs I am firmly rooted in the "I only shoot real black powder" camp. It's largely for practical reasons for me. I shoot percussion, flint and BP cartridge. I have had ignition problems with subs in percussion and am sure it won't get any better in flintlock, so I avoid them altogether. Combined with the fact that BP is more accessible than most folks are aware of, I attempt at all times to advise the use of real BP.
I hereby stand down from my soapbox...