Both those batteries are 99% likely to be the same type in either drill so aren't competition legal.

Henry, those batteries would most likely be fine, they afterall aren't powering anything other than what they are meant to power. As an extra bit Lithium Polymer IS a type of Lithium Ion battery. The particular chemistry used in drills is slightly different being LiNiMnCoO2 which is a safer variant. Also his plan of using those batteries is free but I agree that a 3S LiPo would be a better choice.

One of these ESC's is a solid option that's well priced: https://docs.google.com/document/d/1...X9DFu5AJk/edit