I think I have my robot choice narrowed down to the Maytronics M400 or the Polaris 9450. I was at the local store last night, and the big, single filter basket in the 9350 is making me want to buy it no matter what. The guy at the store that actually works on all these things said the Maytronics would be far more reliable, and when it did break, less expensive to fix. So I took home an M400. After thinking about it, even if I run into a $500 repair in three years when the warranty expires, I might be fine with that if I've gotten 3 years of super easy cleaning.
I'm coming from a nitro cleaner, which worked great, but had a filter bag that was a huge pain to clean. The M400 has rigid cartridges, but there are two, and they don't look like they'd hold very much. The 9350 has a much larger cartridge, and again, popping the top open and dumping that huge basket looks super simple!
My only other annoyance with the nitro was the twisted cable that had to be untwisted every use. The swivel on the maytronics would fix that, and although the 9350 doesn't have it, I've found a few reviews on TFP that say it doesn't really twist too much?
If anyone has experience with both, or just the 9350, I'd love to hear your thoughts.