Kyvol Cybovac S31 Smart Laser Robot Vacuum · Roborock S4 Max

A self-emptying base reduces dust-bin handling to roughly every 60 days, but the mop still relies on a manually filled and emptied external water tank rather than a self-washing station.

The original design and price point were competitive for its class, but that original value is now weighed against a sold-out official US store and signs of a neglected product catalog.

No object recognition: with LiDAR, cliff sensors and a bumper but no camera, the S4 Max maps a room accurately and still drives into the cords, socks and pet messes that camera-equipped models identify and route around.

Buyers wanting a currently purchasable new unit

As of this research, every model on Kyvol's official US store, including the S31, is listed as sold out.

Buyers who need confidence in ongoing parts or software support

The wider Kyvol catalog shows broken product pages and pricing inconsistencies consistent with reduced vendor upkeep.

Buyers wanting a self-washing mop system

The S31 mops from a manually filled external water tank rather than a self-cleaning pad station.

Owners wanting hands-off dust management

The S4 Max charges on a plain floor-standing base with no auto-empty function. Emptying the 0.46 L bin by hand every one to two runs is part of using it, and no auto-empty retrofit exists for this model.

Large open-plan homes over 2,500 sqft

Single charge supports 110–130 minutes runtime on carpet; large floor plans require multi-session scheduling or manual recharge.

Homes prioritizing quiet operation

Flagship models run 65–68 dB; the S4 Max runs 68–70 dB in standard mode. Noticeable in sound-sensitive environments; use eco mode (quieter, slower) for off-peak times.

High-pile carpet with heavy pet debris load

Suction is solid for daily maintenance but trails S8-series flagships. Owners with thick matted carpet or weekly pet shedding may need stronger brush design.