Update: The performance of this robot has only gotten worse. We have renamed it "Marvin", after the robot in Hitchhiker's Guide to the Galaxy. "Marvin is the failed prototype of Sirius Cybernetics GPP (Genuine People Personalities) programme and due to unresolved flaws in his programming he is stuck with the intelligence to do great things but the will and drive to do very little." Fitting.---We own two iRobot i7+s and previously a 960. We recently acquired the s9+, hoping it would help more with our cat allergies and my cleanliness OCD. Our experience:0) The s9 is slightly smaller than the i7, so it fits a little better under furniture. [GOOD]1) The s9 top load bin and filter design is much improved over the i7+. It is much easier to get to and change. We love this new design. BRAVO! [GREAT]2) The s9 maps and covers well. So does the i7. [GREAT]3) The s9 battery capacity is poor for large surface areas. It takes about 4-4.5 hours to do our main floor because it has to stop and recharge for almost 1.5 hours during the cleaning cycle. It's a slight improvement on the i7+. [NEEDS IMPROVEMENT]4) The s9 traverses between hardwood and thick rugs with ease (note: we have NO rugs with fringe edges). It automatically increases the suction when it detects it's on a rug. [GOOD]5) The s9 is great at picking up fine cat hair on hardwood floors. So is the i7. [GOOD]6) The s9 performs the same with fine cat hair on rugs as does the i7. Even with spot clean and setting the s9 to the highest level of suction, it goes round and round and doesn't pick anything up. If we're lucky, it rolls the cat hair into strings that we then have to manually pick up. [NEEDS SERIOUS IMPROVEMENT]7) The s9 has a much larger filter than does the i7. We cannot believe the amount of fine grained stuff we collect in this thing (all I have to do is clean the filter in front of someone, and they immediately want to buy one!) I'm not sure that it does better than the i7, however. I'd have to do a comparison test. [GREAT]8) The s9 is advertised to have an "anti-allergen" feature, but this seems to be nothing more than the filter system, which the i7 has. Both have "high-efficiency HEPA-style (not HEPA) filters which capture 99% of dirt and filter down to 10 microns." True-HEPA which filters down to 0.3 microns. [NEEDS IMPROVEMENT -- as in, REAL HEPA filters]9) The s9 brushes curl under and sheer off entirely, easily and frequently. The i7 brushes are champs. [UNACCEPTABLE]10) The s9 rubber rollers seem to be not be as durable as the i7 brushes. They easily are cut/cracked. [NEEDS IMPROVEMENT]11) The s9 frequently gets stuck. Badly. It apparently thinks it needs to climb the legs on our dining room table and gets "stuck on a cliff". Or it goes between the center legs, gets wedged, and keeps trying to pull through to the point that it takes force to pull it back out. Really? We've started referring to the s9 as "Jarvis, the stupid robot." [UNACCEPTABLE]Rating: C--Overall: we are really REALLY disappointed in the s9+. It was advertised as being great for pet hair and allergies, and yet, it's really not unless the hair is on hardwood. In all, we simply do not see $400 of added value in the s9+. Save your money and buy the i7+.UPDATE: I have to give iRobot customer support a big thumbs up. They replaced the original unit at no cost whatsoever. Given that, I'm increasing the rating by one star. I will also share the following Roomba S9 experiment and results.---Research questions:* Is a Roomba S9+ smart enough to evade pets?* Is a Roomba S9+ smart enough to evade pet "droppings"?* Is a Roomba S9+ strong enough to suck in a cat's tail? (If the Q1 answer is 'no', then this question is moot.)Experiment methodology: * Acquire 2 long haired cats with different personalities. One must be very skittish, and the other head strong and stubborn.* Allow cats to get familiar with the environment and claim it as their kingdoms. * Program a Roomba S9+ to automatically run three times per day, each in different parts of the house. This is important because, for example, we want to determine if dropping location makes any difference (e.g., near the litter box vs. in the middle of the carpet).* Let the Roomba run for months on end and observe.Data to collect:* Contents of home base and S9 waste bins.* Debris on S9 (particularly in the rollers and wheels).* Video of cat behavior.Results:* Is a Roomba S9+ smart enough to evade pets? NO. The S9 runs right into pets. And in fact, cats are able to jump on its back and take a free ride around the house.* Is a Roomba S9+ smart enough to evade pet "droppings"? NO. Not only didn’t the S9 evade the droppings, but it coated the wheels, rollers, and side brush and then ingested the droppings and completely covered the circuit board. A through cleaning resulted in months of circuit board errors, causing it to undock and then die in the middle of the floor. This delayed the experiment. Another S9 was acquired to complete the experiment.* Is a Roomba S9+ strong enough to suck in a cat's tail? YES. If an S9 makes contact with a cat's tail, it will promptly suck it up into the rollers, which will set the cat off. An (probably not so much) unexpected result is that attempts to free the cat from the Roomba should be done with care, perhaps wearing oven mitts and a catcher's mask. Updating flawed methodology that did not take human safety into account.