I bought one of these (EMC/Electric Motorsports GPR-S), but I can't provide any usefull feedback since it's been in the shop since I got it titled. I was trying to get used to it and finding the range but it never went more than 35 mph and I was only able to ride it for a total of 4 miles. It seems the charger had a blown fuse and some of the batteries were bad. The interesting thing is there isn't an apparent indicator of a problem, unless you know what the voltages should be.
Now EMC is telling me it's going to take up to 25 days for the batteries to balance and during this time it can't be ridden faster than 20 mph and a certain voltage can't be exceeded. Martin at EMC hasn't emailed the voltages yet, so I don't know what they are. If I ever get the bike back I'll be sure to answer any questions you may have.
The manual is lack luster and provides very little useful information.
I just hope they start my warranty from the time I get the bike back (if ever) and not when they delivered it.
I've almost sent the bike back several times, but they have convinced me they just about got it fixed. It will go back this week if they don't email the speicifcs of the voltages and warranty.
I've made seven payments on this thing and have nothing to show for it except for a lot of aggravation.