Isn't loose powder a pain in the rear especially in the field?
Otherwise I have heard great things about BH209.
I don't consider it a pain at all. As stated, have you 3 to 4 speed loaders loaded with powder and you can reload as fast as pellets in the field. And I have never found any pellets that you don't have to swab between shots. With BH 209, you don't have to swab between shots.
AND, you are locked in to very specific powder charges with pellets. With powder, you can experiment. Some guns may like 95 gr instead of 90 or 100.