Really, what happens is that because of the increased efficiency of the person + bicyclist combination vs. person walking, you go farther for the same burned energy.
yes, there is that aspect. What about going up hills? I always found there was a point (of steepness) where I could no longer ride, but could still walk.
not sure about caloric impact going uphill on bike vs. foot, but the real limiting factor uphill is the point at which you can no longer balance the bike because the pace has slowed too far.
well, yes, I'd re-mount for the downhill, of course. And yes, the balance thing is interesting. Hmm, on a tricycle with very low gears, I could imagine I might have stayed with that.