Not to just pile on with another 'What Robot should I buy?' thread (although this is really what it is), I've seen some newer, different ones out there and I'd like to get some perspectives.
I've owned two different pool robots and preferred one much more than the other... of course it was also in a totally different pool, so I'm not sure how much the difference was robot vs pool.
Robot 1: Dolphin Diagnostic.
I loved this thing. I had an old, inground, fiberglass pool, about 25,000 gallons, with a deep end. One drain, 3 returns. Basically rectangular. Pretty simple pool. There was a large oak tree that reached over it and provided a steady source of bird droppings, so the robot was essential. The Dolphin did a very good job every time I dropped it in. Sparkling clean in a couple of hours. I never really fell for the hype of how it 'learns your pool, blah blah'. I always thought it just had some logic like, run in one direction for a while, then run in the other, and the offset floating handle just helped it sort of turn at the surface. Whatever, it worked well. The only thing I didn't like was hosing out the 'diaper' full of bird doo at the end. Later, I found a guy who sold disposable filters for it and life was good. Sold that house and left the robot with it.
Robot 2: Got a new house, and built a fancier pool this time around. It's smaller, probably 15,000 gallons. The deepest end is only 5 ft or so. 2 drains (which I think is probably standard now for safety). Gunite structure with pebbletec surface. Has a couple of benches for sitting. Most importantly, it's sort of a very rough 'T' shape. This pool has far less bird droppings (I learned a lesson about the tree! but seems to collect more chunks of mulch and stuff from beds nearby). I went to the pool store and was convinced to buy the new Polaris 'truck' style of robot. It was the first model (9300?). Two drive wheels, jetted water out the back. I was mainly attracted by the fact it had a canister to collect debris which I could just dump out. This thing sucks (or sucked, I guess, since it's dead now). It never really seemed to get the pool as clean. I'm not sure why. I don't know if it had crappy logic compared to the other Dolphin, or it was the fundamental structure and design of the robot, OR if it was just the pool. Anyway, the power supply finally failed, and given the repair cost (sick!) and it's performance, I'm going to get a new robot.
One thing I noticed about the polaris, is that it kind of 'fell off the sides' a bit more (if that makes sense). I think the water flow in these robots makes a difference. The dolphin pulled water through the bottom, and jetted it directly out the top. I think this helped on the sides since it would suck and push itself toward the edge (with the tracks and floaty handle doing just enough to give it upward motion). The Polaris sucked water in through the bottom and jets it out the back, which helps it propulsion-wise. It climbs the sides easily, but I don't think it help push it onto the wall enough. Secondly, that rear 'exhaust' looks like it disturbs a lot of the bottom debris as the robot drives around, making it hard to pick it all up.
Anyway, I thought I'd just get another Dolphin Diagnostic, but that seems to be discontinued. I either can't find it, or the price is $3,000 for some reason (I paid like $900 for mine the first time around). I see at the pool store that Polaris has a NEW robot (and can't find it online) that is the track style. Instead of a bag/filter, it has a canister (which I like a lot). However, because of this, it also does not jet its water out the top (although I'm not sure where it does come out).
So: Any recommendations, suggestions? Is there a currently available track-style robot that people are happy with? Is my pool shape the real problem here? Love to hear any inputs.