I would not consider using that motor driver from pololu for more that 5 seconds. Look at the dimensions (1.5" x 1")
Now look at this one:
http://www.aliexpress.com/store/product/Free-shipping-New-0-24V-Dual-30A-H-Bridge-DC-Motor-Driver-Peak-60A-for-Robot/710410_634914339.html
It's DUAL 10A FULL H-BRIDGE. You can run BOTH DRIVERS IN PARALLEL. Connect the motor to both outputs. Connect both DIR
inputs together and BOTH PWM inputs together. The heat will be distributed between both drivers. The dimensions are 4.2" by
2.2" . The price is only slightly more than the other one and it can take 60A peaks /per single drive. In parallel it could take 20A continuous or 120A peak. The driver will only dissipate what the motor draws so this driver will never burn out. The other one from
Pololu looks very wimpy by comparison. This one is cheaper and looks beefier. (13A)
http://www.robotshop.com/en/cytron-13a-single-dc-motor-controller.html