Deciding on caliber is NOT easy. I struggled with that. My choice, with my Jeager, was between .58 and .62". I had all the .58" "stuff", bullet molds especially. And, I'm a fan of the .58". But, the bigger the bore, the lighter the barrel, and I planned to hunt far and hard with it, and take it trekking and exploring too. So the lighter the better. The other "thing" was that as I hunt in a Grizzly recovery area, the increase in whomp was not a bad thing. Although, I'm not sure what a hot loaded .58 can't do. Or, "was there enough difference to make a difference"?
In the end I went .62", mostly due to the weight, which again, is not that much difference. But when ranging far and wide, every ounce can count. As for power, I can always load the .62 "down" to a .58", in theory? but the bigger bore will always have an edge, when both are loaded as hot as one dares, although at the price of more whomp to the shoulder.
If you aren't spending time in Mr. Grizz's backyard, I don't think you'll be unhappy with a .54". All I hear about them is good stuff. Sure haven't heard complaints about it. People dropping moose and elk with it. And the ball certainly has plenty of weight, way outclasses the .50" bore. It's a good caliber.