but my surmise is that there are very large (relatively) pieces of 447 on the bottom
I concur. I believe that the airplane was intact when contact with the water occured, and that break up was minimum. Given that few bodies and limited debris was recovered leads me to believe that the airplane settled to the bottom rather quickly. If true, then the footprint of major components will not be large, however, a miriad of misc items will make the overall area much larger. The deep water would allow items to drift some distant while sinking.
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