We tried out the s9+ in a 15,000 square feet building with approximately 8,000 square feet of carpet. Unfortunately the roomba would inevitably encounter an error which would force it to cancel its job. And instead of picking up where it left off, or immediately heading back to areas which needed more mapping, the roomba would start all over again and waste hours remapping areas that it was already familiar with. If the software allowed continued mapping after customizing a map, then we could have sent the roomba to uncompleted sections of the map after restarting, in order to finish mapping the entire building. As is, the roomba will likely never finish mapping since it either gets stuck or gets lost and aimlessly wanders after a couple hours.