The things on the S6X aren't to make it smoother...
The design idea for it is that you can put a different shaped piece of plastic on there so that the hull characteristics could change. The downside was that you had to buy an extra package for it and it was hard to get and I don't ever think i saw one. I wouldn't say you need to do anything about the scratches on the boat. If anything I would say going at it with a heat gun would do more then sanding it, but either way its not gonna effect anything hugely. One thing that it may effect is the sharpness of a harder rail, so the carving might get worse, but the Delirium doesn't have really sharp chines to begin with. So, in other words, don't worry about it. Any sand paper that would do anything to large scatches in Prijon plastic would probably just make it worse anyways. Have fun with the boat, should be fun for ya.