Another (mostly) happy multiple Neato owner here. We are older, and have a bigger single story home. We started out with an xv21, which worked well, but was very loud, and took all night to clean our house. Since we have 3 cats, and live in the desert, we vacuum every day to keep hair and dust to a minimum. This unit is 2 1/2 years old, and other than a couple batteries, still works every night.
Within a couple months of us buying our first one, woot had one of these on sale. Realizing how much work this saved the wife an I, I bought it to split the workload. This was a significant step up from the SV series, as it ran longer, had a bigger dirt bin, and was quieter than the XV. Unfortunately, right around the first of the year, it developed a fatal issue, and figured after two years of daily cleaning, a "new" one was in order.
So, we bought another refurb from Amazon. This one started off working well, but after about a month won't dock. i spent a month troubleshooting, buying a new battery, etc. For the past month, I've been trying to get Neato to fix it. Still waiting for "supervisor approval".
Bottom line, these work well. They have some "quirks", but you quickly learn how to work around them. Once you have your house and routine set up, it is awesome to wake up to a clean floor every morning (we run ours at night when we are sleeping). They require very little maintenance other than cleaning out the filter every other day. About monthly I will vacuum and blow out the whole unit, and use 3 in 1 oil for the small rollers that get really squeaky.
I'm thinking about giving this one a try. But, if you do, get the extended warranty, just in case.