I feel like it's to "textbook-y" for it sound like something Rachmaninoff would have arranged. He would have embellished the melodies, added daring counterpoint, played around with the rhythm, and added a little bit more of a virtouso flair to the piece - to completely transform it into a piece solely for solo piano. Right now it still sounds like just an arrangement, however it is a very good one. I enjoyed it!