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Robot vacuum comparison
The Roborock S8 Pro Ultra and iRobot Roomba j7+ are the two most bench-tested used robot vacuums on the Robot AutoTrader platform. They score 9.1 and 8.7 respectively — but they are designed for different households. The S8 Pro Ultra is a full vacuum-and-mop system with an autonomous dock; the j7+ is a vacuum-only machine with best-in-class obstacle avoidance for pet homes. The used price gap is around £200–£300, and choosing the wrong one for your floor type is a real mistake.
Robot vacuum & mop
Robot vacuum
| Aspect | Roborock S8 Pro Ultra | iRobot Roomba j7+ |
|---|---|---|
| Type | Robot vacuum + mop | Robot vacuum only |
| Bench score | 9.1 / 10 | 8.7 / 10 |
| Used price (UK) | £580–£720 | £340–£430 |
| Retail price (new) | £1,099 | £549 |
| Dock system | Full RockDock — self-empty, self-wash, self-refill | Clean Base — self-empty only |
| Obstacle avoidance | AI-based, good but not pet-waste specific | PrecisionVision camera — designed to avoid pet waste |
| Mopping | Active mop with auto-lift on carpet | None |
| Best for | Hard floors, mixed hard/rug, mopping required | Pet households, carpets, obstacle-heavy rooms |
| Best buy month | September | August |
Choose Roborock S8 Pro Ultra
Choose the Roborock S8 Pro Ultra if your home has significant hard floor area, you want the mop function, and you are prepared to pay £580+ for a dock that genuinely handles itself. It is the better machine overall and the right choice if mopping is part of your requirement.
Choose iRobot Roomba j7+
Choose the iRobot Roomba j7+ if you have pets, particularly if pet waste avoidance matters to you, or if your budget sits under £450. The j7+ is a more focused machine — vacuum-only — but its camera-based obstacle avoidance is the best consumer implementation available used at this price.
Bottom line
For a mixed hard floor and carpet household without pets, the S8 Pro Ultra wins on performance and convenience. For a pet household on any floor type, or any home with a tighter budget, the j7+ is the smarter used buy.
Yes, if mopping is a requirement. The S8 Pro Ultra adds active mopping with an auto-lift mechanism that raises the mop pad when it detects carpet, plus a dock that washes and dries the mop heads autonomously. If you do not need mopping and primarily have carpets or a pet household, the j7+ performs as well as the S8 Pro Ultra on vacuuming alone and costs significantly less used.
The iRobot Roomba j7+ is the better choice for pet owners. Its PrecisionVision camera-based obstacle avoidance was specifically trained to identify and avoid pet waste — a unique capability at this price point that the Roborock S8 Pro Ultra does not match. The j7+'s 8.7/10 bench score was achieved in a two-dog household with daily use over twelve months, making it the most directly validated option for pet environments on the Robot AutoTrader platform.
Both are depreciating at a similar pace. The Robot Resale Index shows the S8 Pro Ultra at 91.8 (down 8.2% year on year) and the j7+ at 93.2 (down 6.8% year on year). The j7+ holds value slightly better, likely because the j7's obstacle avoidance generation retains relevance longer. Neither is an appreciating asset — both are best bought used and replaced with a new model in two to three years.
For the Roborock S8 Pro Ultra: confirm the full RockDock is included and run a complete self-wash cycle before buying — listen for pump noise and check the water lines. Without the dock, the listing should be priced well below £400. For the Roomba j7+: confirm the Clean Base dock is included, and check the PrecisionVision camera lens for cloudiness or scratches. A fogged lens is a £60–£80 repair.