If you want to win a race there is only one importance. Speed!! The trick with recumebnts comes down to aerodynamics. The les wind you catch the faster you go. Each year there is a race at Battle Mountainfor the absolute speed record. The current record is set at 144 kph. The bikes they use for this are only good for going fast in a straight line. Most recumbent races are held at a velodrome or a street track. So being able to steer is also a factor. Most Dutch races are held by the NVHPV.
The wind is the biggest brake if you want to go fast on a bike. Recumbents become fast by laying down behind your feet. This way you minimize catching the wind. The diference between seat height and bracket height is often more than 20 cm.
If you are racing you want al your power to go towards speed. Often more comfort means less speed. That is why a stiff frame is key. Most race recumbents have no suspension or a very stiff suspension. This way every pedal stroke means speed.