I have tested it against several other robotic models (9300, Dolphin DX5) and it did well. The 4 wheel drive was certainly and improvement from the 9300. It still got stuck on the toe-kick (in a fiberglass pool) sometimes, but overall it did a good job cleaning the pool. The DX5 also did well (handled the toe kick and stairs better than the other two). In my opinion, the best part about the 9400 (and 9300 for that matter) is the cartridge. It is much easier to clean than the bags that come in other robots. Let me know if you have any other specific questions about it.
