Is there any advantage to either in a traditional rifle shooting roundballs?
IMO, Pyrodex is better for PRB shooting. In my experience, I have been unable to find a T7 load that does not blow patches, regardless of patch/ball fit or the amount of powder used. I have never found a T7 load that will shoot consistently with a PRB in .45, .50, or .54 caliber, even when used with a Wonderwad on top of the powder.
The stuff works great for conical bullets with a Wonderwad under them, however.
It is much easier to clean up at the end of the day if you used T7 all day than if you used Pyrodex. But I have never had to wipe between shots to reload when using Pyrodex. Not so with T7, however!