Any advantage of dutch lap over traditional lap vinyl siding?

Overall there is little advantage between the two. I would go with the product that looks best for your house. If you use a high quality (40 mill or higher) vinyl siding either will look nice if installed properly. Dutch lap fits tighter at the overlaps due to the extra bend. Often times, traditional lap siding, if "stretched", will cup at the seams, Dutch lap in general is not a prone to this problem as bad. Don't focus this minor problem, just make sure you get a good product and hire a reputable installer and you house will look like new again.