Wish I could help d / halfnote. I'm not a banjo kind of guy and I think CEB can provide better info. Marty Stuart has two Scruggs tuners on his Telecaster on the 1st and on the 6th string along with a B bender.
Basically they allow you to drop tune and come right back to the original tuning. How? I'm not sure on the banjo! The B bender on Teles work off of the front strap holder. They drop the B string, when you raise your shoulder and come back when you lower your shoulder. Many of the newer models have a large chrome knob on them right behind the bridge that works like a whammy for the B string only. Mainly used to get a steel guitar sound. Some guys like Junior Brown can drop several whole steps on a stock Tele using the 6th string, by ear, and using the tuning machine, come right back to the original tuning while playing a boogie tune