If someone is going to make an arguement that we should only use a "superior" projectile for hunting with a muzzleloader I think we are treading on a slippery slope. It would logically follow that we should only use a "superior" firearm. No one could argue that most centerfire rifles are "superior" to even the best muzzleloader.
I do not get hung up on thinking I need to use a roundball or a conical just because it is more traditional. At the same time, if I am confident that that roundball or conical will do the job it is intended to do and I know I can put them where I am aiming, I have no qualms about hunting with either.