Tunesmith posted that tantalizing link to a Clarence White clip, and Tony Rice has been mentioned above, so i figured we ought to include an example from Dan Crary playing in the DUDUDUDU mode--he was about the first solo "flatpicker" I was aware of--and was a great influence on guitar players who wanted to play bluegrass--

I am leading up to the idea that, far from being "traditional", even in terms of bluegrass, "flatpicking" is a work in progress. No matter which picking pattern you start with, you have to expand your range, and grab techniques where you find them in order to develop the range of options that are needed to be a full fledged soloist.