Gas-powered aircraft don't have transmissions, and gas engines tend to only be efficient in a narrow band, so I'd guess that the RPM limitations of an electric

Gas-powered aircraft don't have transmissions, and gas engines tend to only be efficient in a narrow band, so I'd guess that the RPM limitations of an electric motor (which can generally tolerate a wider range) wouldn't be an issue as long as it's a reasonably-engineered motor. Beyond a certain RPM range electric motors lose torque. Eventually you'd reach the limits of the bearings or the maximum centrifugal force that the rotor can withstand, but that's usually at a higher RPM than gas engines are made to survive. I would expect an electric motor designed for an aircraft would be optimized for maximum power/efficiency at whatever RPM band is optimal for the propeller, and the battery would be optimized for whatever voltage is optimal for the motor at that RPM range.