Adding some science to my observations above, this study shows an endurance increase even in the short term, 45 minutes, from modifying the pedal stroke to a more smooth circular pattern:
http://www.radlabor.de/fileadmin/PDF...MSS_-_2011.pdf

Searching on the web, I found it notable that there are a large number of websites which refer to the 1991 Coyle study as gospel, as though the science of pedaling dynamics had come to a halt then and there.