Richie credits Niles with saying The singing technique had voice-breaks, slides, and high, rasping wails. All of the "coon shouter" videos on Youtube seem to be white people singing vaudeville versions of ragtime blues ( Sophie Tucker doing After You've Gone), and the technique displayed contains very little of slides and rasping wails. Now, the style might have been considered radical in its era, but sounds pretty contrived and theatrical today.
I'd love to hear the original source material.