Well I own both a .50 and several .54's...and others but I will stay on topic...,
I was looking for a particular style of rifle when I bought mine. I wanted a very simple flintlock, with a swamped barrel, something that could've been "common" at the F&I War and later in the AWI. What I found was a .54, BUT I would've still bought it had it been a .50. So I think you're fine with a .50.
NOW as far as "versatility" goes, a .54/.55
smoothbore, is a 28 gauge shotgun, and can be used for both round ball and shot, but a rifle is a rifle.
Perhaps you mean versatility when it comes to game harvesting, but I think the .50 will harvest what a .54 will harvest. As for hogs, a boar is not a feral pig, and a large, European bore might be a problem for a .50 , but that's a powder charge problem too, not just a ball size problem.
LD