For a fixed bridge instrument like an acoustic guitar, the string size makes much more difference because the bridge has to be properly compensated (distance from the nut increased slightly from the theoretical scale length, to make up for the string stretching slightly as it is fretted), and that distance will change with changes in string gauge. For a banjo or guitar-banjo, (or most mandolins) you can slide the bridge around to compensate it for the strings you've got on it. Keep in mind also that, disregarding other considerations, lighter strings are generally easier to play than heavier ones.