The group I hunt with uses them exclusively. We’ve harvested 25+ elk with the 250 FTX. We don’t shoot long distances and make sure of shot placement. We’re using the MMP 3 pedal EZ sabot over 100 grains by volume of BH209. We’ve never lost an elk to one.
We used to use the Barnes muzzle-loader bullets with great success too. In our muzzys the FTX seems a little more accurate and way easier on the budget.
We never had good terminal success with power belts.