I don't care for 209 caps, I find them hard to handle. No. 11's with real black powder have never presented a problem. I have a T/C Scout that would not shoot Pyro Pellets, we thought that would be the cats meow one year, I used magnum No. 11's and it became reliable again.
Bottom line,for me, if I use loose Pyrodex or Black Powder it doesn't seem to matter what ignition source I use.