to guest Jim, GERRY O CONNOR uses CGDA, It has certain advantages it gives a brighter sound, but certain tunes like THE HOME RULER, cant be played as the notes are not there,[ it goes below c]. the advantage of cgda is you dont have to fret higher, thanthe 2nd fret for your top B, Instead of having to go up to FRET 7, and do all that jumping, with the pinky.
If you learn g d a e you can pick up a mandolin and with only a little bit of work you can play both instruments.
I have two banjos tuned different ways,.
you can put a capo on2 fret with cgda, and play along with gdae players, effectively your 2 fret fourth string becomes the same as a gdae players third string. Dick Miles