Hi all. In my robotic applications I often use Victor 883 speed controllers:

http://www.ifirobotics.com/victor-88...ler-robots.htm

Now, this controller has a couple of advantages over the EVX...

A. It has a faster switching frequency...less heat and more efficiency so run times are longer.
B. Finer speed increments...better control
C. Up to 30 volts!!!

I'm contemplating trying one in my E-Maxx with some higher voltage motors. The controller uses the same PWM interface as regular RC controllers. It would be interesting to see if two 12v motors in series on the Victor would be better than two 24v ones in parallel.