With respect, buck-&-ball is much better suited to combat than to hunting. Just ball, or straight buckshot if required or preferred, would be better for hunting large game. For buckshot use, a 10 or 11 bore would permit efficient use of larger shot sizes and larger charges than would the French 14 bore. Fit of the different stock designs might come into play. Other than these, the considerations would include that a larger bore is likely a heavier weapon, would more easily handle larger shot charges, and might have heavier recoil, especially for ball loads. There're probably other considerations, but others will likely add them.
Regards,
Joel