I had a Dolphin Dynamic for about three weeks - it was terrible. Did not clean that well, and then just started going back and forth in a 10' straight line without leaving that area. Fortunately I bought it online from Costco, so I just took it back to the store and got my money back. That was something like three years ago. I got a Blue Pearl to replace it, and it works great. It has run with no issues until a few weeks ago when the little internal drive belts that take power from the motor to the traction belts wore out. Bought new ones online from ebay for $20 and now she is back in business working great.