earl scruggs was among the handful of great instrumental innovators in twentieth-century american popular music. comparable figures are people like louis armstrong, little walter, jimi hendrix. the banjo in his hands yields an amazing combination of rhythm and melody: it's the most percussive of the string instruments, and scruggs created the role of the banjo virtuoso in bluegrass: during his solo, he drives the band faster and faster, like an accelerating train. the other people i mentioned above actually played behind the beat, giving their playing a kind of relaxed swing even in a furious solo. but actually earl has somewhat the same effect: you start wondering whether there's any limit to his speed, and then it almost sounds easy. still the right expression playing like that would be a grimace of extreme concentration, like roy clark.
you hate to say someone shouldn't change, but the semi-electric earl scruggs revue albums in the 70s with his sons etc were not very good.