I have the Polaris 280. I’m happy with it. You won’t get many people on this form to comment on pressure side cleaners - they love their robots. That being said, I have one because it came with the pool. Do I think a robot is probably a smarter decision, yes. But for folks that have the majority of what they need like the parts, pieces and pumps, it’s a no brainer. My advice is find a used Polaris. They can be worked on easily and are relatively simple to work on. Does stuff need to be replaced, yes. Same with robots though and you can’t always do that work yourself. I keep saying I’m going to break down and buy a robot, just doesn’t make sense to. I like the idea of my cleaner being out of the pool - just looks cleaner and neater. So I just take my Polaris out and put it in from time to time when I don’t feel like fooling with my other methods. I actually bought one of those cheap manual hand pump cleaners and use it pretty frequently. I’m in the pool and I enjoy it. Truth be told, other than the electricity use, I don’t think robots are all that much better. I still see people complain about all the same issues as pressure side cleaners. Check eBay, get one used and see what you think. Be prepared to do a little work and order a few parts. If you decide down the road to make a change, do it. Best of luck with your decision.
PS - I like that trivac you posted. Never heard of it until you posted it, but the fact I’ve never seen or heard of it would concern me a bit. Looked on amazon and only available by third party sellers. Would think if they were all that, they’d be stocked by amazon... just my opinion though.