I guess my question for all you advanced techie types out there is, "are hand movements less effective for maneuvering?"
I know that for myself, I can quickly get myself moving backward much more easily with my hands than I can with my attempts at a back kick, and while I can probably turn just as effectively using helicopter turns, I can do it quickly and easily with my hands as well.
As for swimming, I broke myself of that habit some time ago. I think it goes without saying that that is inefficient, but I'm a little skeptical that I'd actually see any difference in my sac rate or any significant improvement in maneuverability if I stopped using my hands entirely.