I've noticed that I can more quickly/easily approach the top end of the EV power range with EV/PWR than with EV/ECO, where the gas pedal feels more sluggish (as designed to)
I don't think EV vs HV matters, only whether it is in ECO, Normal, or PWR modes. All it does is change the throttle response. For example, if you press the accelerator the same amount in each of the modes, ECO will accelerate a little less than Normal, a PWR will accelerate a little more than Normal. Pg. 247 of the Owner's Manual states: