My 2012 S had no real issues during the 8K miles that I rode it, other than needing to be rebooted upon first startup each morning when the bike was cold and it continues to run fine for my daughter. So far, "knock on wood", my 2014 power-tank equipped S has run perfectly once the power tank was properly sorted out by a Zero technician. I continue to believe that most of the issues that some owners are having with their Zeros have to do with sloppy assembly, either at the factory and/or when repairs are made by their dealer's technicians. Perhaps the factory workmen should slow down a little and take more time to make sure assembly is being properly accomplished.
There doesn't seem to be anything wrong with the Zero's design or components or everyone would be having problems. So, to my mind, that just leaves issues caused by assembly mistakes, such as the incorrect assembly of wiring or connections and that can be, and should be, corrected at the factory.