Performance wise, the Spitfire Mk XIV is closer to the 1944 Spitfire Mk IX than is the AH Spitfire Mk IX.
It doesn't really matter though.
There is no way to set one of these up so it works right. I fly Mossies mostly, but in this proposed environment I would be facing Fw190D-9s, Bf109G-10s and Me262As.
The Germans built 700 Fw190D-9s, yet that is what I'll face 95% of the time a 190 icon is seen. The thousands of A series Fw190s that would be represetnative of this time period will sit unused in the hangars. The same is true for the Bf109s. Not that the AH Bf109G-6 is representative of a Bf109G-6 of July, 1944 any more than the AH Spitfire Mk IX is representative of a Spitfire Mk IX of July, 1944.
On the RAF side you have Typhoons far in excess of their historical numbers and 1942 Spitfire Mk IXs that weren't even in service anymore.
I think the likely American balance will be closest to correct, with a heavy de-emphasis on bombers.