Price: Both Have Been Discounted With Age
At launch, the $1,099.99 Combo j7+ was significantly less expensive than the $1,799.99 Roborock S8 MaxV Ultra. Both models have seen their share of discounts around holidays, and as they’ve aged. At the time we're publishing this comparison, Amazon is selling the Combo j7+ at a midrange price of $594.99; the S8 MaxV Ultra still has a premium, but now more reasonable, discounted price of $1,299 at Best Buy. As usual with robot vacuums, the prices of both will continue to fluctuate, though I expect you’ll find the Roomba model for less than the Roborock almost all the time.
Winner: Roomba Combo j7+
Design: Roomba's Robot Is More Compact
Both of these robots are disc-shaped and come with big base stations designed to help with upkeep. The Combo j7+ robot is the smaller of the two (13.3 inches in diameter by 3.4 inches tall) compared with the S8 MaxV Ultra (13.9 by 13.8 inches in length and width, and 4 inches high). While the differences in the size of the disc won’t make much practical impact, the lower height of the Combo j7+ will help it fit under furniture more easily. The base of the Combo j7+ is also more compact at 13.0 by 12.5 by 15.0 inches (HWD) versus 18.5 by 16.1 by 16.5 inches for the S8 MaxV Ultra.
Winner: Roomba Combo j7+
Navigation and Obstacle Avoidance: LiDAR vs. vSLAM
The S8 MaxV Ultra navigates using a combination of LiDAR and an AI-equipped camera for obstacle avoidance. The LiDAR sensors sit in a tower on top of the vacuum (the main reason it’s taller than the Roomba), while the camera resides on the robot's front edge. In contrast, the Combo j7+ navigates with the help of visual simultaneous localization and mapping (vSLAM) technology and has a camera to detect obstacles.
I won’t get into the nitty gritty of LiDAR versus vSLAM, but in short, the former uses lasers to create a 3D map by measuring the distance between detected objects and walls, while the latter uses visual features and landmarks for pathing. Different systems aside, both clean in systematic rows and support home mapping, so you can set up keep-out zones and send them directly to a specific area or room for targeted cleaning jobs.
When it comes to avoiding obstacles, the Combo j7+ did much better than the S8 MaxV Ultra in our real-world testing. The Combo j7+ stayed clear of clutter on the floor, whereas the S8 MaxV Ultra ran over pet toys during testing. Moreover, the Combo j7+ comes with the aforementioned one-year Pet Owners Official Promise (POOP) guarantee that it won’t smear pet waste.
Winner: Roomba Combo j7+
Vacuum Performance: Both Deliver Sufficient Pet Hair and Dust Pickup
The Roborock S8 MaxV Ultra has an impressive 10,000Pa of suction power, a spec iRobot doesn't specify for the Combo j7+. Both do a fine job of picking up dirt, dust, and pet hair from different flooring types. Additionally, both models have a self-emptying dustbin.
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The S8 MaxV Ultra's high suction power helped it perform particularly well on our vacuum stress test (removing sand from carpet), though it did tend to fling more particles than the Combo j7+ when cleaning hardwood floors. The S8 MaxV Ultra has a concealed scraper underneath its brush roll that keeps it clear of tangles, a nice feature if you have long hair or live with shedding pets.
Winner: Roborock S8 MaxV Ultra
Mopping: Roborock Excels at Scrubbing and Self-Maintenance
The winner of this category will likely depend on your home. If you have carpeting with a medium to high pile that you really don’t want your robot to dampen as it works, the Combo j7+ is the better choice. When it senses carpet, the mop lifts out of the way and rests on top of the robot, thereby avoiding contact entirely. The S8 MaxV Ultra uses a more commonplace mop-lifting mechanism. When it senses carpet, it simply raises its mop, so it's still under the body of the vacuum, just not touching the floor. It can only lift the mop by 0.79 inch, which is enough clearance for low-pile carpets, but it will still brush against anything higher.
That said, the S8 MaxV Ultra actively scrubs your floors, vibrating the mop 4,000 times a minute, whereas the Combo j7+ mostly just drags its mop, and sometimes moves it back and forth over heavily soiled areas. Additionally, the S8 MaxV Ultra has a secondary mop that extends out to the side for more thorough edge cleaning.
The S8 MaxV Ultra also requires much less mop maintenance than the Roomba. Its base station washes and dries the mops with hot water and hot air, respectively. The Roborock's base also has separate reservoirs for clean water and detergent to keep the robot topped up between runs. With the Combo j7+, you have to wash the mop pad yourself, either in a laundry machine or by hand, and you have to manually fill the robot's water reservoir before each run.
Again, which is tops in this category will depend on your home and preferences. But if you have mostly hard flooring, go with the Roborock for its self-sufficiency and scrubbing power.
Winner: Roborock S8 MaxV Ultra
Smarts: App, Voice Controls, and More
Both of these models connect to Wi-Fi, support app control, and work with Amazon Alexa and Google Assistant for voice control.
In addition to the above, the S8 MaxV Ultra doubles as an indoor home security camera with two-way audio. You can steer it remotely from your phone, send it on automated patrols, or even have it look for and snap a picture of your pets. The microphone also allows you to issue voice commands to it directly via its built-in assistant, so you’re not reliant on a third-party intermediary device like a smart speaker or display.
Winner: Roborock S8 MaxV Ultra