The J9+ Combo is one of the only two robots currently on the market that purport to be able to keep medium-pile carpets/rugs dry. The other is the Dreame L20 Ultra. I got both and pitted them head-to-head. The J9 is the only one that succeeded in this goal. Note, others, like Ecovacs and Roborocks can't lift their mop pad high enough to clear medium pile carpet.I've been using the J9+ daily for 2 months now, and it has performed fantastically; and I've been using top-end robots from several manufacturers for many years. Unlike others, it created a perfect map on the first try, has never gotten stuck, detects/respects rugs, and avoids objects well.Pros: • Great mopping performance. Got off stubborn stains in less passes consistently in numerous mopping tests of different substances, such as dirt, sauce, milk, batter, cocoa, etc. (see measured test for example) • Great vacuuming performance. In my embedded rice test on shag rug, Roomba J9+ picked up 64%, compared to 42% from the L20. • Great mapping (see pics) and navigation. Just detects and handles rugs properly. Efficient pathing, never misses a spot. I don't recommend doing a mapping run. I just did an initial "Clean Everywhere" with only vacuum, and that produced a perfect map, and did so just as fast as when the map is already in place. Tested and compared mapping on a total of 5 floors across 2 homes. • More conservative object avoidance, probably owing to the P.O.O.P. guarantee. I don't need this and prefer more aggressive, but might be important for some users. • Less obtrusive dock. • Can clean under drapes and bed skirts, and not befuddled by glass doors and mirrors, like LiDAR-based bots. • Quick and easy to replace pads. Stored in dock. Recommend buying 12 more for ~$40 then only need to wash once a month. • Less long-term maintenance. Changing a pad on the top of the bot, from a stash stored in the dock, seems less work than: dumping dirty water, cleaning bottom of dock, refilling clean water 4x as often, and replacing pads every 1-3 months, as with L20. • Less complex, less mechanisms to break down (LiDAR, self-cleaning, self-drying). • Runs immediately, doesn't have to take time to wash pads first. • Cleans faster. • Quieter when not running (no dryer hum). • Simple procedure to clean unknown room: 1) Carry to target room and press button; 2) it will immediately clean whole room and return to where it started. • Can co-exist with active family. You can walk around it while it works, and it's quiet when it's not working. • App is better designed and efficient. Can do everything in less steps. No limited combinations of settings. Can clean favorites, zones, custom rooms, everything, with Google Assistant voice control. • Works on 5GHz Wi-Fi. • Good object detection of cords and backpack straps (even low-contrast), as long as they are not stretched out in a line.Cons: • Would not mop bathroom unless I removed mats. No indication of why. Guessing there needs to be a certain amount of available hard floor to deploy mop. • Doesn't mop within 2" of edges. • More frequent bumping. Doesn't bother me, but can be disconcerting to others. Doesn't do any damage. • Doesn't navigate well in the dark, however does work reliably in some cases, such as cleaning my kitchen. • A little louder, both bot and base. Measured 65db for base empty, vs 60db on L20. • Eats stretched out cords (no matter the contrast) • Leaves too wide of a berth around obstacles, typically 1'. • Each time switching to the app takes about 5 seconds to connect. • No spot clean button! • Mop arm elbow sharp and close to ground. When on a side angle due to one wheel on fireplace hearth, possibly ripped off piece of my floorboard that might have been sticking up a bit. Resolve by no mop zone around raised areas. • No Android widget. • Recommended to change mop pad after each use.