Strong, light and aerodynamic Starley TT/Triathlon frames are designed to provide maximum efficiency for the rider when in the aero position. Get these bikes up to speed and time yourself against the clock, low and fast is Starley's mantra.
If you're not convinced about a Time Trial bike and going all out aero then consider the current world hour records. 49.7km on a Road bike, 56.375km on a Time Trial bike. It's all down to aerodynamics, not extra power. The rider accounts for upwards of 70 percent of the drag in the bike-plus-rider equation. The power you need to overcome aerodynamic drag on a bike is related to your drag coefficient (determined by shape and surface), frontal area, air density and speed. You want to lower your drag coefficient and frontal area while making sure you can still ride your bike. There's no point in having an extreme position if you can't pedal, but changes in position take some time to adapt to, so give them a chance.
Starley TT/Triathlon bikes are designed to minimise drag from the bike itself but also to maximise the reduction in drag the rider can achieve by being set up to ensure correct body positioning.