Vis-a-vis Nelson's approach to improvisation, that NOCTURNE date is very revealing, IMO. The title track is "through-composed," Strayhorn meets Debussy, and is as much a study of articulation, subtle timbral variation and vibrato as it is anything else. Probably a little less of that Trane influence / processing going on here as well. Check out the "build" on Nelson's solo on "Azur Te"...