Charles Neidich, who has made a careful study of the Premiere Rhapsodie, has said that Debussy always intended it to be with orchestra. He made the clarinet/piano arrangement at the last minute, and it had a number of errors. However, he meticulously corrected the solo and orchestra score, which represent his final intentions. The printed edition represents his final thoughts. It's at http://www.woodwind.org/clarinet/Music/Manuscripts/Premiere/debussy.pdf.