Originally Posted by fhhuber
The sure things to compare (if the maker is honest) are:
Max input watts (note that max usually is at max voltage and assumes adequate cooling)
Useful voltage range.
If these 3 are the same you can expect to have motors that will perform the same even if shaped differently.
And if you find a motor is rated at 150 to 200 watts or even more, per ounce of motor weight, read that rating with a real big grain of salt!