When my throttle was connected to my BBS01 250 watt average power crank motor, at PAS 9, when operated only by pedals and the motor, the power won't go beyond 250 watt input power. When the throttle was used, the power was around 600 watts. Part of this is firmware configuration which can be changed. I reckon as supplied, my system draws about 7 amps from the 36 volt battery when pedalled at a high pas setting and about 15 amps when throttle is depressed at the same pas setting.
So in my case throttle certainly uses more battery, but this will depend entirely on how your own particular system is set up, and what PAS setting you are on.
If i could connect to my own system controller, I could reconfigure it. At present I can't. I may have a bad cable supplied on ebay.