I'm pretty much clipless now, though I'm still using the toe clips on my mountain bike because I haven't spent the money on a second set of pedals. (Frogs on the road bike, stock toe clips moved from the road bike to the mtb.)
While I'm riding, I've been contemplating the idea of pulling up on the pedals, and experimenting a little bit. I don't think I'm naturally pulling up just because my feet are clipped in. When I do knowingly pull up, I can feel it in all sorts of tendons and ligaments and the hams. Since it's been a few weeks, those feelings are going away, I guess as I made saddle adjustments, getting used to it, etc.
Also, I keep my shoes pretty loose because my toes swell and get numb. When I pull up consciously (and hard), my feet can leave the bottom of my shoe (depending on the conditions). I chose shoes designed for spinning because they seemed to have more vents than regular road shoes, plus I wanted tread, but not bulky mtb shoes. The guy at the LBS said they were fine for road biking, as long as I wasn't planning on hiking out of the woods with my bike over my shoulder.
I think all my thinking and experimenting boils down to this question. Is it a conscious act to pull up--a skill to be learned--or is it a natural result of the physics of being clipped in? Am I doing it whether I think about it or not?
Karen