My B/D is going into its 3rd season and works like a champ! My only problem is it does get tangled into my ladder so I have to pull the ladder out--only a minor pain.

I had troubles with my Dolphin remote-controlled. I finally figured out why, and why the B/D can do the pool so much faster: The impeller motor on the B/D has to be 3x as large. On the Dolphin it's the size of a frozen OJ can despite being much heavier than the B/D. On the B/D it's the size of a Morton container of salt--so it's got FAR more power as a vacuum and to hold the unit via suction to the walls.

See, they are actually very simple gadgets with cool brains. One motor is the impeller--a simple fan that creates suction for the vacuum and holding the unit down. Then there is one or two motors (two for the fancier units) for the drive. When it hits a wall the s/w reads the change in current demand from the motor, and knows it's hit a wall and decides to either go forward (climb the wall) or reverse. From that, and the number of motor rotations it maps the pool! Conceptually very simple, very elegant. There's no sensors I know of in the unit so that HAS to be how it recognizes a change or a barrier.

But the Dolphin never got tangled on the ladder....