The substitutes may be necessary in Canada.
In the US, black powder is easily mail ordered for a competitive price. Powder doesn't need to be available local. Puts too much costs on local shops due to storage regulations and prices will not be competitive anymore. Just store a decent supply at home. The less black powder is sold overall, the more expensive it will become over time. And substitutes only work in percussion guns.
I shoot the cheapest reenactor powder for around $10 and that included the Hazmat and shipping. It was $200 for 25lbs + shipping and hazmat fee when I bought it. Shoots as good as more expensive powder unless you are a constant 10x offhand shooter. I shot exactly the same group sizes with reenactor than with 2F.
A little more dirty? Maybe, maybe not. Depends largely on the climate and your wiping routine.
On a percussion revolver, the biggest PITA is cleaning the 6 nipples anyways, the rest is a breeze. .44cal 1851 Navy here.
Black powder will stay exactly the same over time if kept in the cans. The newer plastic cans are even better, because they don't corrode anymore.
Caps still need to be stored in a dry location and only some brands come in plastic tins.
A lot of people should seriously get off the "I can't buy it in my local store" wagon.....