While I agree with Carbonfiberboy and LV2TDM in theory, my contention is that it is different system due to human anatomy. In the case of a locomotive the power curve through the stroke of the engine is same regardless of load (especially with electric motors where the torque cure is linear and constant through the entire 360 degree cycle), however, with us frail humans, the power output is not a constant, there is a bio-mechanical feedback mechanism in place that will automatically adjust your power output when things start to move. I realize I am on somewhat shaky ground here (I am an engineer, but of the electrical variety), but I do know we do not output instant power and hold it constant (as Carbonfiberboy alludes to) through the full turn of the crank. Otherwise, we would be breaking lightswitches and ripping car doors off their hinges as we open them. As a result, I expect the stoker to have a problem maintaining constant peak power through the power stroke due to the crank being accelerated away from them due to the captain. I would think the experiment I proposed of swapping positions and comparing results will either prove my intuition correct or strongly suggest I not quit my day job
