Thinking aloud, since a lot of aerial vehicles are going unmanned, one would think this would work as a full size model. And with that, the applications it could be used for.
http://www.mikrokopter.de/ucwiki/en/MK-Okto (http://www.mikrokopter.de/ucwiki/en/MK-Okto)
I believe Boeing tried this about 30 years ago with using some H-34's (IIRC) joined together by a frame it was a spectacular failure as the harmonic vibrations set in and it beat itself to death. You can probably find it on Youtube.
Are you thinking of this as a manned aircraft? I would think the issue would be with scalability; The total power to weight ratio is not so hot due to all those individual power plants. There are military and police versions of this designed primarily as ultra-miniature "remote viewing" platforms, where the trade off for short flight time is multiple axis video ( 360 degrees of rotation), low cost, ease of operation, low noise, and minimal operator training. Its not an efficient way to fly in the thermodynamic sense of the word, and the failure of a single rotor or motor would be cataclysmic. It would however, be mega-cool.
Major Lord
I have a hard enough time keeping tabs on one rotor system!
I was thinking only unmanned. I'll look up the H34's, didn't know about that one.