OK, not that complex, but more than the typical 3 chords found in a bluegrass song:

Summer Fly (Cheryl Wheeler)
Coal Tattoo (Billy Edd Wheeler)
Sing With the Angels (Rick Fielding)

We've tried all of these at bluegrass jams and watched everyone drop out, turning it into a performance rather than a jam.

The "subjective timing" refers to pauses and retards and other personal expressions and tempo variations that you might find in a folk song rendition but rarely in a bluegrass song.