[Al Skierkiewicz]

There is no limit on speed controllers or Spikes. The limit is on motors. However, robot electrical rules dictate that certain motors need speed controllers only and may not be powered by a Spike.
<R54> All electrical loads (motors, actuators, compressors) must be controlled by relay or PWM
output signals sent by the Digital Sidecar to an appropriate power regulating device
A. Each CIM motor and Fisher-Price motor must be connected to one Victor or Jaguar
speed controller. They must not be connected to relay modules.
B. Servos must be directly connected to the PWM ports on the Digital Sidecar. They must
not be connected to speed controllers or relay modules.
C. If used, the compressor must be connected to one Spike relay module.
D. Each other electrical load (motors or actuators) must be connected to one Victor or
Jaguar speed controller or one Spike relay module.

That being said, several teams have been ordering the Banebot "RS545" motor with transmission attached. Please watch for an update on this particular motor. For now if you are using this motor combination, I would recommend using a speed controller only, not a Spike.