The EyeX eye tracker uses less expensive hardware components and is also just a part of a development kit, which means that there are no products included (yet).
An application that hooks into DirectX games to override mouse input would be nice. It is not supported out-of-the-box, but we expect that 3rd party developers could easily implement this kind of functionality using the EyeX SDK.
Regarding the accuracy and precision of the EyeX Controller: it is not satisfactory yet, but the algorithms and firmware is still under development and we expect a number of improvements in upcoming software updates.