My only criteria for getting another robot vacuum is whether it can detect and avoid a maliciously placed cat turd.
I know the Roomba wouldn't have survived my rabbit, too many raised plastic edges and no ability to avoid him. I would be interested in seeing if the Neato would be capable of entering my rabbits territory over concurrent visits. Although I'd definitely have nightmares of the rabbit hijacking the Neato.
On the upside, it gave me a chance to take the thing apart completely. Roombas are very meticulously designed and are built for being taken apart. It matches up completely with their policy for allowing and encouraging modification of the firmware.
I just wish I didn't have to deal with feces to learn that :S