The power increase (i doubt it's that high) doesn't come from changing the pedals but rather the shoes. Stiffer soled shoes will transmit power better and distribute pressure across your whole foot. platforms on the other hand (assuming you're riding with sneakers) after a while cause your feet to go numb because of the flexible soles and the pressure point of the pedal axle. The clipless advantage really only comes in the form of stability. hit a rough patch of road and your feet will never slip off yet if you wipe out you disengage immediately.