Tim, the only reason why we use the heavy speed 900s is because they have good torque for a good rpm range.
The fact they are hugely overpowered in total for a feather is a sideline in that equation.
But yes, even on 7.2V they have enough power for a feather. (and still have a usefull RPM of 4000)

The Astros are a good motor to build a featherweight Storm II. (but so are the speed 900s)