Any question answered...

I'll let tester summarise his experiments with short cranks and cadence

If you keep gain ratio constant, you'll do the same speed, within any practical range of crank lengths. There might be marginal differences from the following sources:

1. Shorter cranks reducing effecting frontal area and therefore reducing drag
   
2. Higher cadence increasing downstream turbulence and therefore increasing drag
   
3. Higher cadence increasing metabolic cost due to more frequent muscle firing
   
4. Higher pedal force increasing metabolic cost due to greater muscle force and length of contraction
   
   

If 2 didn't cancel out 1, and/or 4 cancel out 3, there would be a clear choice between long cranks/low cadence and short cranks/high cadence for racing cyclists :)