All the problems with Quarks were, a bad ESC (replaced for free), a bad motor, etc. The Schulze however, not so great. They are smooth, I'll give em that much, but there not reliable. Leroy is the only person I know what hasn't burned it up....And thats unusual for him :confused:. Anywho, Schulze has no customer service to speak of as well...Just look at Serums Hall of Shame...