What is the "current eveidence seems to indicate" on the high cadence = longer effort.
I believe that when I go out on a 4-5 hour group ride that I will last much longer (and have more late-ride energy) if I do the high power sections (usually hills) at a higher cadence. It seems that the high cadence, though it does slightly limit my power, takes less energy.
Which is the key? The high cadence or that I'm using slightly less power (not red-lining as much)? Or both?
Well, you'll somewhat lower Type 2 recruit by limiting torque. That being said if your power is lower then that would obviously allow you to go longer.