I just purchased the Dolphin M400 and after one use I am very happy. I did not get the optional Remote because I didn't think I would use it. I now think it would be nice to have to get the cleaner over to the steps to take it out (I'm not as strong nor flexible as I used to be). The M500 Remote is only $10 more than the M400 Basic Remote so I am interested if anyone has tried the M500 Remote with the M400 and does it provide the additional functions the M500 has (scrub waterline, etc).