iRobot Roomba Combo j9+

The mop arm is the part worth understanding, because it solves a problem the spinning-pad machines only manage around. Instead of lifting a wet pad a centimetre and hoping, the arm swings the whole pad up onto the roof of the robot and holds it there while it crosses carpet. One pass handles a room with a rug in the middle of it, and nothing gets damp that should not be.

What the dock does and does not do is the other half. It empties the bin and it refills the robot’s water, which between them cover the two chores that quietly kill robot mopping in most homes. It does not wash the pad. That stays a hand job every week or so, and anyone stepping across from a self-washing dock will notice the difference immediately.

Noise is the honest weakness and it is not close. The emptying cycle is a short, hard blast that owner reports routinely describe as unignorable from another room, and iRobot’s own framing is that this generation’s base is quieter than the last one rather than quiet. If the base has to sit in a hallway outside a bedroom, this is the wrong machine no matter how good the rest of it is.

Navigation is camera-based rather than laser-based, and that has a consequence nobody mentions until it bites. Owner reports are consistent that runs in a dark room go badly, because the camera needs something to see. Cleaning at night with the lights off is not a mode this machine really has, which sits awkwardly next to the fact that night is when you would most want it running.

The reason to choose it anyway is everything that happens after the first year. Rollers, filters, and bags are stocked in ordinary US retail, warranty handling does not begin with an export form, and the app has been around long enough to be dull, which in this category is high praise. Balance that against a company whose finances have been reported on heavily, since a warranty is only ever worth what the firm behind it is worth.