I live in Texas and don't close my pool up for the Winter, the Polaris 360 runs 365 days a year for about 10 hours a day. I just installed my "2nd" Polaris 360 because I've reached the point where the previous 360 is in need of yearly significant maintenance ($100 or more). I am at the point after 10 years that my previous 360 needed a new body, a factory rebuild kit, and hose wall connection. When I considered the cost of those parts alone, I have over 1/2 the cost of a new one and the new one comes with a new bag + pressure hose + back up value etc. When I considered looking forward over the next few years, I'd have to add other parts, I figured the "sum of the whole was less than the sum of the parts."
Now some more comments. I also have been a previous owner of Polaris 280 sweep that used a booster pump. They clearly work better, but you have now added another expensive item, the booster pump, that adds expense by having another electrical hog running and will eventually need repair work. This is why I didn't choose a booster pump driven sweep on my 2nd pool.
I am also a owner of a Aquabot Turbo that I used about 8 times a year because it takes more attention. It is effective in picking up items, so after every 6-8 hour run I find I must pull it out of the pool and clean the bag. The Polaris will run for 1/2 a week without requiring attention to the bag (but it's not as effective). I also have found if I don't take the Aguabot out of the pool and allow the cord to "dry out" the cord tends to be more likely to be tangled up in the rollers on the Aguabot (I think the foam might get water logged but this is based on my experience) I use it mostly in the Spring to help prepare my pool for the swimming season It does a good job at just over the 2x the expense of a Polaris 360. And if the bag is kept fairly clean, it will climb and scrub right up to the coping (yes, partially out of the water).
So why a 360? It does a decent job of keeping the water sediment stirred up for the filtration system to remove and vacuuming the items like sand, stones, sticks and leaves off the pool bottom. It does have a hard time climbing walls, and thus I've never had success with it climbing the stairs or very far up the walls. Little to no added electrical cost is a plus for me. The down side is of course the parts as they wear out. Locally the pool supply stores provide the labor for free if you buy the parts (Leslie's is one example). I learned that when the feed hose starts to go, you can just repair the failed section, but you are likely going to discover over the course of the season that each section starts failing, so to remove frustration, I'd suggest replacing the hose at once.
So over 10 years, I did one factory rebuild kit in the 5th year, probably 1 bag a year, 3 to 4 tail sweep scrubbers every year, about 8 tail wear rings, 1 back up valve in year 9, a new feeder hose with swivels at year 6 and a few other miscellaneous parts. Last season I noticed the neck on my 360 had lost a piece where the bag clips on, so if I wanted to "repair" it was about $60 for a new body. I do notice that when kids swim, they rarely remove it from the pool and thus are often tempted to stand on it. Understanding that this pool sweep is sitting in chemically treated water and running 10 hours each day, it's bound to wear out and need maintenance. I think if your expectations keep this in mind, you'd probably be happy with it.
So it's not perfect, but for me, the cost is reasonable to the benefit of not having to vacuum the pool or tend to the pool sweep as often. My summary is that it wasn't until the 4th season I started seeing maintenance becoming more than just replacing items that are expected and meant to wear out like the tail scrubber, silt bags, wear rings, etc.