I have a Nautilus CC Plus which I have had for about 4 years. Like others have said on here, the robot just moves aimlessly throughout the pool during a cleaning cycle going over the same area multiple times while missing somewhere between 20-40% of the pool. I have to run it through about 7 cycles to get my ~30x20 foot 35000 gallon pool somewhere close to 100% clean. Do the newer models like the Sigma not miss so many spots, or is it better to just get the cheapest cleaner with a manual control option?