Nnoitra high diff. I highly doubt that Senzonzakura wouldn't be able to cut through his Hierro considering the sheer numbers of them, Byakuya's versatility with them, and enough speed to wear out Nnoitra. Eventually, his petals will be able to cut into him with techniques like Gokei and Senkei. Of course, that's base Nnoitra.
A Released Nnoitra will get nothing more than scratches. He'll just tank through Senbonzakura, catch Byakuya off guard, and tear him apart.