slowrotor,
That idea of ten little motors spinning you into the air has little merit, for two reasons:
1) A number of smaller disks never gets the same disk loading as the single large disk of a helicopter, because all those little inscribed circles that you envision cannot equal the area of the single large helo rotor. Try to draw 10 circles inside one big one, and shade in the area that the small rotors waste - the area between the little rotors that is "lost" because you have too many disks. This lost area is about 40%, and demands that your little rotor solution always has higher disk loading and less efficiency and uses more power than a single rotor solution. Don't think of shrouded rotors as a solution, shrouded rotors never gain in efficiency what they lose in weight over open rotors. The few lift systems that used shrouded props all failed.
2) Think hard about why cars do not have 6 small engines - the greater the number of power contributers, the less the overall efficiency of a system. A twin engine aircraft is about 10 to 20% less efficient than a single, and a three engine is 20 to 30% less efficient, and so on. That is why the world is going the opposite direction that you are in seeking fewer engines to solve the performance problem.