Heck, you don't live that far from the fellow, go speak to him on the subject yourself. He's the man when it comes to pedaling analysis.

Jeff Broker, Ph.D., former biomechanist for the U.S. Olympic Committee. Broker currently serves as an assistant professor in the biology department at the University of Colorado at Colorado Springs. Armed with years of pedal-force graphs obtained from ongoing studies of elite cyclists at the Olympic Training Center in Colorado Springs,

Broker has separated out the gravitational and inertial components of a pedaling force diagram, so that one could really see exactly what was being produced and at what cost to the rider. According to Dr Broker, pulling up on the pedal does not increase maximal power output, and in fact it can cause injury. Pulling the pedal up puts a lot of pressure on the hamstrings and the hip flexors. These muscles are designed to lift the weight of the leg against gravity whilst running or walking and struggle to cope with the demand of contracting repeatedly against the resistance of the pedal. As the muscle fatigues, this increases tightness, which can contribute to lower back and hip pain. In addition to this, at recommended cadences of 80-90rpm, the muscular system cannot contract and relax quick enough to deactivate one group of muscles and contract another. In other words, as the left leg pushes down, the right leg cannot get out of the way quick enough to create negative pressure on the pedal, let alone generate force in an upwards direction.
In short, pulling on the upstroke does not work. So what is the correct pedal technique? Dr Broker advocates directing all your power into the downward stroke, starting the stroke at 12 o’clock, and ending it at 6 o’clock. This is termed the ‘drive phase’. As the drive phase is coming to an end on one leg, it should be beginning on the other leg, while the first leg relaxes. Peak torque during the drive phase should occur around the 3 o’clock position."

Sorry, I don't have more time to spend going through all his work at the moment but I thought he said in one of his papers that he downstroke contributes to > 90% of the force on the pedals.