I have to say: I love my Roomba; this device meant I had to use an upright once in the past three years - when I moved out of my previous apartment. And one of

I have to say: I love my Roomba; this device meant I had to use an upright once in the past three years - when I moved out of my previous apartment. And one of the things that I love about it is that it's simple. It uses a random walk for its cleaning algorithm, which means that it gets its job done on the average if you let it run long enough. Random walks are easy to understand. I can re-position furniture in my apartment to make it a bit more Roomba-friendly, or I can shift an office chair before a run to make sure Roomba gets under the table when I'm going away for work. The nice thing about it is that there's nothing that can break in this scheme. It's dead simple. If Roomba doesn't get to a corner, I know exactly why, and what to do about it. With persistent maps, that aspect is out of the window. If a Roomba doesn't map your apartment right.. good luck figuring out how to deal with it. KISS, I'll keep repairing my Series 600 until the spares run out.