Having sold hundreds of the Dimension Engineering controllers, only about four have failed of which two were from Gary. I never advise on suitability of using drill motors unless the spec can be produced for them. Over volting drill motors is an added unknown and is at your own risk really. 24V Gold's should be fine, I'm not comfortable using 12V Gold's though as it is a bit borderline.

Paul
http://www.technobots.co.uk