i used a blue 50a speed controller in mine origination, with a 12v car seat actuator over volted to 14.4v and it ran fine and could pick up 24+ kg but ive change to servo and two micro switches (i think its known as a bang bang controller) only changed it because i changed my transmitter to a pistol grip version and the 3rd channel doesn't work with speed controllers

these are the 50a esc
http://www.ebay.co.uk/itm/Marine-50A-Sp ... 35c3fbd852

at the moment im using a these or a similar version to run both my robots and they drive them round quite well so should do as another option for and actuator
http://www.ebay.co.uk/itm/High-Voltage- ... 20cffabd44