I have 4 7-string banjos. They are a real hoot to play. Years ago, I was jamming with Don Pedi, playing one of my British (unmarked)ones at the Festival at Mt. Airy, North Carolina. A few campsites away was Mike Seeger, Pete's half brother, playing an old Martin.
When he heard that 7-string, he followed the sound like a dog smelling steak, and we picked all afternoon, Mike has, unfortunately recently passed away. He had an extwnsive banjo collection.
I never got to show him my Orpheum 7, with a 12 inch head and tone ring. You can vamp all day on the low 2 strings.