Let me start by stating that I haven't even tried to figure out RAW files yet. Now on to the question. Using a 20 D if you shot three pics of the same subject, in three sizes ( S, M, L jpeg fine ) and all three pics are exactly the same, when you crop (no resizing) a 12 x 8 section (the same section out of all three) can you get more detail, thus sharpness, out of the large picture.

