10 horsepower is 10 horsepower as far as I am concerned. The gasoline engine will have a governor I would expect and there is a lag as the governor does it's thing compared to an electric one that has the electric grid to call on at the speed of light. I think this is where the idea the numbers do not exactly yield the same results in the real word. Maybe as you overload an electric it draws more amps that the plate on the motor says while the gas one is out of it's rated peak power spot. A 25kw tractor pto generator claims it will start a 10 hp motor and it does almost always if it doesn't do not try for very long or the capacitors (start capacitors there are rum ones as well) will make a puff of smoke. It does not seem to trip a 40 or 50 amp breaker when connected to the grid. On mine they have soldered a little resistor across the capacitor terminals that shortens the space for the clips to attach and think that has caused me some aggravation. I have the Cooks one, It comes with switch gear that I think is 40 amps it appears to be for three phase but not all the terminals are used. I think It is 40 amp but not sure without going out to verify. The pto generator I use the 50 amp plug with breaker and it only is rated at 100 amps but to use that steady you need connect to another spot. I have tripped the switch gear breaker engaging the engine too fast (it starts no load) not the one on the generator. Mine uses a 3600 rpm motor and I suspect the other manufacturers do as well but it is possible to get a somewhat heavier motor that has more torque but half the rpm.
