Toughest part about this particular design for me is the assembly & maintenance. Presumably the motor would be mounted, and then the motor pinions pressed on. It'd take a pretty specific press setup to do this successfully without damage to any other mounted motor. Then if a motor burned out, figuring out which one to replace is tough. After that, replacing the motor is equally tough since it doesn't appear that a gear puller could get in there well enough.
All of these can be alleviated to an extent via design considerations, so I'd be interested to see what you come up with. At the same time, if 1 motor fails there are 5 more to keep something running - this redundancy is really nice for open-air motors. The dead motor provides little resistance in the form of friction or back-emf, so it's a decent redundant setup.
As for utility of this design - finding a way to use cheap motors is always a plus to me. We can get away with splitting wires off of a controller in the 'real world'. This message board seems to forget that nifty/niche designs usually have more use outside of FRC than the typical FRC design
