The PRB is the most effective, I have had both the sabot barrel is no more effective than in a 50 but the PRB is the most effective of the PRB calibers it is the flattest shooting and if you load it right it put most well hit deer down on the spot. I use 110 gr RS in the 1in 48 twist 120 in the 1 in 66 twist and 130 in the 1 in 80 twist. I have been using a 54 PRB since 1980 and have taken deer boar and black bear with it as well as using it in long range competition at 177 yds.
My advice is that a 50 for sabots is good but the 54 is best with PRB.