I keep hearing about the "almighty" double C tuning. What exactly is the attraction? I can play in C, granted without the low bass C, in standard G. And maybe I haven't adjusted enough to it, but there doesn't seem to be as much versatility as with standard G.
I suspect that the reason many of the Briggs tunes don't use the bass string is that they pre-date the adding of the bass string (some time around 1840), which makes them ideal for playing on a 4 string gourd banjo. I do switch my bass string back and forth for a few tunes, but try to leave it low for the majority of tunes.