I'm still curious about them but feel mostly the way you do. I purchase or build rifles with a slow twist with the full intention of using round balls and I work at finding a load/patch combination that shoots balls well. The real benefit to this sort of ammo is clearly that it provides more energy, all other things being equal, so if someone has a load that fires very well out of their rifle with the PA conical, I can't find any fault with them for using it. I guess I'm even more curious and interested if they make it in a .45. I know that thousands of deer have been killed with .45s and even smaller caliber roundballs, but personally, I lean towards the .54 more and more (though I built myself a .50 and killed a doe with it this fall).
I have a .36, will be adding a .40 very soon, have two .50s and one .54, so I'm building myself a .45 at some time soon. Again, I know that a .45 roundball is capable, but I've had plenty of poor blood trails and long tracking jobs with .50s and even .54s after a well-placed shot, so if I'm going to hunt deer with a .45, I at least want to consider the possibility of using a heavier cast bullet. We'll see.