Full wheelslip, I would not normally call this a stall... the train is stalled, but not the motor.
With those gearboxes, it's very hard to actually bear down to get a full stall condition on the motor, theoretically the max possible current draw (would be nice to design the electronics to handle this), but full wheelslip is normally your practical worst case condition.
I believe you have Aristo SS rail as I do. This is much slipperier than brass, so you should be able to achieve full wheel slip at a lower current.
Also, you did not have the full 6 pounds of weight, right? that's another variable.
Just trying to point out to all that the question "what is the max current draw of a Dash 9" needs a whole bunch of qualifiers, especially if you are measuring full wheel slip, not a full motor stall condition.