[Vexs]

I can see that potentially being a problem, especially if dirt or something gets caught in it. However, the most delicate part of it is the most replaceable, that band could be easily made out of cloth or leather, and motors are usually fairly available. It's most certainly a better argument than "it's not much power" etc, but I'm not convinced it matters too much. I doubt just as much as the next guy these things will change the world, but it's a noble idea and a noble purpose.