Hmm. Looks interesting in writing at least. The question begs to be asked - why a mountain bike? Think of all the juice being used to shlug those heavy tires. Since it isn't actually designed for off-road, why not switch over to lighter, more efficient wheel? My guess is that it would extend the range at least.

What are the grey boxes hanging off of the rear carrier? Are those batteries? If so, a 15 mile range for those honking batteries doesn't seem like much. Again, maybe lighter more efficient wheels/tires would improve the range.

I too am looking forward to hearing some feedback from owners of these machines.