swatman,
I've got a .50 cal TC rifle. I shoot nothing but conicals, think I'm using TC Maxi-hunter. Mainly I'm lazy and don't want to patch the ball when reloading. Probably does cost more, but as I'm only shooting about 20 times a year doesn't matter.
As I remember from my Lyman load book, the maximum black powder you can use is less with a conical vs. a round ball. Will look tonite and report back if no one else has prior to then.