Even at weights balanced for "fairness" as Stoney alludes to, the D40 does indeed slightly edge the N in Mil climb and turn. I believe its even slightly faster on Mil.
However, the D40 does not out-climb, out-turn, out-accelerate, out-roll, OR out-run the Spit16, or a whole host of other nasty beasties any Jug in the LW MA is likely to recieve unwanted attention from. The P-47N can percolate at a level speed on the deck that challenges the P-51D, for 5 minutes at a time anyway. Not only does this allow it to leave in the dust things it might be useful to run away from (Spits, N1Ks, etc), it allows it to stand a much better chance of catching things one might highly desire to chase down (190s, 109s, P-51s, hell, even a Lala if you've got some alt to convert.)
So until they give us a P-47M or a perked "field mod" D that can pull the historically ubiquitious 72" manifold, realistically speaking the P-47N remains the way to go.