Paul - couldn't agree more.
Dave:
If the speeds and gearing are similar, then the motor RPM must be also. The calculations bear this out, using typical motor values:
13.5 motor @ 3300kv, at 3.7V = 12210 RPM
21.5 motor @ 1600kv, at 7.4V = 11840 RPM
So the motors indeed rev to similar speeds. However current draw has nothing to do with RPM in a motor, only torque. While all motors have an RPM/V coeffient known as kv, they also have a torque per amp coefficient called kT which is rarely discussed.
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