I am really intrigued by this discussion. I love the Briggs-Meyers test (and can typically pick out the profile for most people with whom I have regular, personal interaction). I would guess that, in general, the I vs. E would have very little to do with abilities on this site (though I would imagine that I's are more likely to play in this format and would devote more time to press, generally speaking). I think that N vs. S would be pretty evenly balanced, perhaps with the N's taking a slight advantage due to their ability to think "outside the box." I would imagine that more T's play Diplomacy than F's simply because an F would have a hard time getting over a stab (though I would guess I've played with a few F's on this site). P vs. J is, I think, more like the I/E dichotomy and wouldn't have a lot of bearing on play.
As far as myself, I'm an INTP - fairly strong in all of those. I don't know that I've finished enough games on this site to provide a strong enough sample (just 24) but in those games I have:
7 victories (2 Austria, 1 Russia, 2 France, 2 Germany) ((all in PPSC games))
10 draws (2 Russia, 2 Turkey, 2 France, 1 England, 1 Germany, 2 Austria)
7 survivals (3 Italy, 1 Russia, 1 England, 1 Turkey, 1 Austria) ((all in PPSC games))
So my percentages are:
Austria - 40% Win, 40% Draw, 20% Survive
England - 50% Draw, 50% Survive
France - 50% Win, 50% Draw
Germany - 67% Win, 33% Draw
Italy - 100% Survive ((God, I hate Italy))
Russia - 25% Win, 50% Draw, 25% Survive
Turkey - 67% Draw, 33% Survive
Pretty strong in the center (A/G) and with France. Italy is clearly my weakest (though I'd be interested to play Italy now that I've switched over to WTA).