Don't it seem a little strange the BH209 has characteristics so different that any other black powder or substitute. Shelf life, cleanup, ballistics, requirements for ignition, etc.
Ummm, no, it doesn't seem strange. It's marketed as a substitute to the other black powder substitutes. Its intentionally designed to offer the same or better performance without the pain in the ass problems associated with the other stuff.
IME not hydrophilic like the black, pyrodex, 777, goex, white hots, etc... That means it doesnt draw moisture like them.
IME its not corrosive. So in addition, to not drawing moisture, even if you somehow get it wet it won't rust the crap out of your rifle, components, or turn into a brick.
Its a high performance powder when loaded properly. 90 grains (volumetric) and a 250 grain bullet groups 3" and sometimes better at 100 yards off my trigger stick. Shot Hornady SST last year for the first time (all I could find at Scheels at last minute) and they shot 1-2". I was also impressed with their performace on 2 bucks my daughters killed.
Regarding the primer discussion, I've used Winchester "blue box" shotgun primers, Remington 209, CCI, and never had a FTF. I'm not picky and just buy what's available. I shoot a CVA Accura with BH breech plug. I also used BH successfully in a Knight rolling block without the hammer (can't remember the model). Knight offered a loose powder "power stem" breech plug, burning the powder from the breech towards the action. It used the red discs and was a tremendously accurate rifle. It would shoot MOA at 100 yards.