More power from the batteries will come ONLY from a higher voltage.Voltage is pressure that pushes the "juice"(amperage).So 8 small batteries of 1.5 volts each=12 volts,like a car battery.The only difference is you will have the same power,but for a MUCH longer time.So 1200ma or 1600ma = a time question,but not a power question,if the voltage remains the same (A glass of water and a swimming pool...).The indicated 12 volts drill battery,delivering a true 14.2 volts,is a good start between power and durability of the electronic and mechanical pieces,from my point of view.Good luck!

Well, I've got a coupla DeWalt 12v batteries kicking around. I'd like to increase my torque, maybe I'll give it ago. I think it's gonna be more limited by the capabilities of the motors themselves, but only one way to find out, eh?