The whole issue of Niles's compositional methodology is richly complex. In some ways, an attempt to understand a three-dimensional human and artist is bound to fail if we attempt to judge him or her in terms of "authenticity," "revivalism," "composer," "arranger," "plagiarism," and such static and judgmental terms.
       Niles grew up in a "folk" environment in Kentucky, learning many a song from his father who was a "traditional" singer. Niles also studied "art" music at the University of Lyons and Cincinnati Conservatory. He was a singer of opera, of popular songs, folk songs, and original songs. He was a part of the folk revival scene and participated in Newport, etc.   Conceiving of him as a "folk musician" or a folk revivalist is really a red herring--he was really coming from a vaudeville mindset....the transcendence of high and low art, the popularizing of music through stories and dramatic presentations.
      He did write original songs that were based on a kernel of a traditional music fragment....I Wonder As I Wander, Black Is the Color, Venezuela, Jesus, Jesus Rest Your Head, Lass from the Low Countree, and Go 'Way from My Window are all original compositions in HIS version. In each case he adapted a fragment--a line or two, or in Black Is the Color, an entire text. He was sometimes ambiguous in his claims of authorship for a variety of reasons, but generally he was pretty accurate about what he did and did not do. Lawsuits always proved his claims to be correct. He kept very careful field notebooks from 1906 onwards that can generally authenticate his claims. Niles had an observant ear and eye, and he was a natural collector who recorded a wide variety of music. His purposes in collecting were diverse--natural curiosity, a desire to create a personal repertory, and a scholarly passion....Some of it he adapted, some he performed exactly as he recorded it, some just langguishes unused in note books.   I am finishing a biography, available in a year, that should clarify some of the veil of confusion that still surrounds his music.
    Like many another musician--folk or otherwise--he took what he found at hand, and made it his own through performance style, or song & text adaptation. Similarly, his "duicimers" were influenced by the lap dulcimers he encountered early in life, but he created his own "Nilesitars" (as Jean called them) in his own image to match HIS needs, his singing voice and his accompaniment style.   A performance of Hangman was very much a personal, idiosyncratic, stylized version of the traditional ballad, complete with colorful introduction, dramatic acted out cradling of the hanged person with the dulcimer, etc. This was striking performance of the song, though no one would ever accuse it of being an "authentic" re-creation of a folk ballad. Niles, the vaudevillian merely wanted to sell the song and the story. Niles the opera singer wanted to sell the drama of the narrative. Niles wanted the audience to experience the essential drama of this marvellous ballad.
    I have very much appreciated reading the thread, and am indebted to you all for caring enough about this music to participate in this continuing discourse. I hope that my few comments may contribute something to the dialogue, and I welcome the opportunity to attempt a clarification of any issues associated with Niles that I can provide based on archives at the John Jacob Niles Center for American Music at the University of Kentucky.