For a 46 inch print to look sharp with your face against it, is that 300 dpi? What prints so large at 300 dpi?
I print at 240dpi, but don't get me started on peoples preconceptions on print resolution and how printer software dithers dots
I shot it with a 1Ds MkIII and a 100mm L Macro at f7.1. Native resolution is 3744 x 5616, I then re-sampled it in one go (I did all the tests in PS years ago and one step re-size works best for me) to 7488 x 11232, that prints at 240 dpi to 31.2" x 46.8", the tiff is 84.1MB, exactly four times the size of the .CR2.
Here is a 700 x 700 px crop from the eye and eyebrow, to get a better idea of the print in person zoom your browser so it is just under 3" square, or print it out at 240dpi. Obviously at this size and viewing distance dof becomes minute, you can see it fall off even in the hairs less than an inch off the eye.
That is what we can do with 21mp cameras, and that is why I, personally, don't need or want
more MP when they inevitably come around.