I did try the ball-et in my Traditions Trapper. In all fairness, I didn't get to spend a lot of time on load development, so I'm sure I wasn't getting the best results possible.
I never did get it to shoot as well as a PRB. As the powder charge increased, the groups shrank, so I think the secret is to load it relatively hot. Recoil was starting to become a bit stout and I remember warnings about Trappers splitting stocks if they're loaded too heavy, so I stopped. It looked to have potential, I just didn't get to do as much testing as I would have liked.