If you search the web there are very many equivalent devices with from 3 to about 8 props, but all are small devices, typically about 400 t0 700 mm across. They are all gyro stabilised and some have amazing manoeuvrability- I've seen videos of these things sticking themselves upside down to a ceiling or a wall using reverse thrust. The commercial driving force is, I suspect, micro surveillance devices. Some have gps receivers so can be made on command to home back to a start location or keep station over a specific point with a sort of dynamic positioning system. Here are such devices:
http://www.multiwiicopter.com/produc...opter-multiwii
http://vimeo.com/23010622
http://vimeo.com/groups/multicopters/videos
The man capable one is just a scaled up version (you can see what I think are the batteries duct taped to the frame) and therein lies the problem- I think they are getting to the point where from a weight point of view carrying a lightweight gas driven generator would give you much greater endurance, and if you also kept some battery capacity for emergency power, much greater safety.