this may stir up something of a controversy, but it's my opinion (and my opinion is often worth about what you just paid for it... i.e. free) that PRB will do the job just as well as a conical. having said that, it's your absolute right to shoot conicals or anything you want out of your rifle, and if it makes you happy, more power to you.
but if left to my own devices, i'd keep shooting roundball and spend the money on powder.
results may vary...
at worst case, you'll spend a few bucks, most or all of which you can probably get back if you decide that conicals isn't all that great anyway.
in either case, make good smoke!