How about the energy lost due to the wheel having to spin the cranks and push yer Pumas?

If the cranks push your foot around at any point when you're actually pedaling, not waiting around or slowing, then you're doing something very badly wrong. As in, cannot ride a bike at all. That's the main fallacy of the schlerojunk. It just doesn't happen.

When you get on yer FW bike after the FG, do you find yourself coasting when you're trying to accelerate?
Thought so...

Even if it did happen, it'd suck energy out, not add more.

actually this happens to alot of people who ride fixed exclusively. They learn to rely on the pedals to pull thier feet through the top and bottom and end up with a ridiculously choppy pedal stroke when they go back to a freewheel.