I did some quick checking this morning, after a bit of flying last night.
Let me preface this by saying that last night was the most enjoyable time I've ever had in the AvA (CT, etc.).
I flew the Spit I last night, got into several 1v1s with Easyscor in an A6M2.
This is just a commentary on the planes and stats, not anything more or less.
It seems as though the Allied planes are at a bit of a disadvantage looking at the stats. As of this morning when I checked -
The A6M2 was carrying a K/D of 1.5, with its K/D against the Spit at 1.79, vs the P-40 1.44, and vs the Hurricane 1.2.
The 109 was carrying a K/D of 1.49, with a K/D of 1.7 against the Spit, 1.68 against the P-40, and 1.07 against the Hurricane.
The 110 is doing the worst, with a K/D of only 1.28. 1.31 against the P-40, 1.27 against the Spit, and 1.25 against the Hurricane.
The Hurricane has the best K/D for the allies at .86, followed by the P-40 at .67, and the Spit at .65.
Perhaps it would be a good idea after all to have the F4F included in the planeset.
What I find really interesting is how awful the Spit seems to be doing. I came out the worst in most of the fights I had with Easyscor, the Spit just didn't seem like it could keep up at all with the zeke. I think the only kills I got on him were from him losing control and augering. I stalled out a couple times and did some odd floating leaf stall into the ground - the Spitfire certainly does not seem to be a very forgiving airplane (which is odd, considering how docile all of the rest are, bar the Spit 14).
Perhaps I will try the Hurricane out tonight, I know from flying the two in the DA furball area that the Hurricane is much more agile (in my opinion, anyway).