At 25k and below, the Spit I is the fastest plane in the scenario. Also, it turns better than all the LW planes.
As for historical accuracy, we have the best planes for accuracy that are available in AH. I bet we get the He 111 at some point, and then we'll use mostly those -- that's the biggest gap for this particular scenario.
One thing to keep in mind: For the scenario, we have LW:RAF of 1.56:1. In the real Battle of Britain, (LW fighters + bombers available):(RAF fighters available) was more like 3:1. With mostly He 111's instead of Ju 88's, probably we'd need to up the LW:RAF ratio a bit -- but we'll see when the time comes.