I've got the Pentair Rebel. It's a copy of the "The Pool Cleaner". It didn't do a good job until I got the speed right and the tyres broke in a bit. I don't think vacuuming walls is a necessity, and it didn't go up the walls at first. Once I got the flow up to around 24 GPM (90 LPM) and the tyres roughened up a bit, it went up the walls to about 500 (20") below the surface. That works for me because I don't want it going near the surface and sucking air. Mine stayed in the deep end 2/3 of the time until the tyres broke in. I brush the pool myself in about 20 minutes once or twice a week, so I'm not worried about brushing.
I have nothing to compare to other than one mate with an MX6 who is not thrilled with it. FWIW, when I pointed to the MX6 and MX8, the pool store said too many moving parts and the vanes near the intake get clogged easily. They also sell the "The Pool Cleaner" in high numbers (it's a warehouse store). That is their top recommendation, but they haven't had any issues with the Rebel, so they said save the $100 difference. I won't know any better until a few years from now, but it runs smoothly without any clunks or grinds. I tried a Barracuda which they took back, thankfully, because it had trouble with our right angle corners and I didn't like the thumping noise ringing out via the fence glass. Both the Barracuda and the Pentair handled the big hard gum leaves here.
I really wanted a robot. I was dead set on the m500 centre brush job. I got scared off when I heard of people only getting 3 or 4 years out of them, cause they're $2K+ down here. I wonder if that might be people who leave them in the pool more than needed. If I ever have a big pool, I would get a dolphin for sure, for the brushing.
I was away for a while and the pool got a nice noticeable layer of dust. You could see the Rebel tracks and how it covered the pool. It was tidy in about 2.5/3 hours. Not quite as well as I could do with the manual vacuum, but very close. By the next run with the Rebel, it was just as clean as I can manage with the manual brush (day before) and vacuum (next morning). My take is that the Rebel saves me around 20 minutes per cleaning vs. brushing and vacuuming manually. (50 minutes manual, including 20 minutes to brush and 30 minutes to vacuum real slow). I get a beer in my hand vacuuming either way, so all good.
