There is the possibility of tuning your banjo up or down so long as the intervals are right for the key you're working in, and the strings will take it. Many early players had no idea, nor did they care, what tunings they used.
re the above bluegrass devotees and their conterparts in blues, mountain music and the like -- I don't understand the idea of faithfully reproducing the exact same sound that a great singer/musician from the past gave us. I'd rather listen to him or her or them. But I'm waffling.