I have been looking at all the different models and reviews fro all the different Dolphin robots and have been getting so confused on which to get. I have a small pool and will be taking the dolphin in and out as needed for cleaning and not leaving it in pool so it seems a basic model will be fine but then I don't get the differences between the Doheny Discovery, Dolphin Nautalis, and Dolphin S200 other than prices. I want it to include waterline cleaning. Any help would be great