Both were excellent fighterplanes. And up against eachother there was not one that dominated the other.
They were both different planes with different charasteristics.
Are we going to see that in game?
If I am flying in a Spitfire would I try to persuade the BF109 fighter to get in a turn and outturn him or when I am flying the BF109 I do 'Boom and zoom'?
Would you like to have assymatrical warfare or would you like to have all the fighterplanes feel the same?
Easiest to balance but less interesting.