Actually, Isegrim has nice and vast array of data on his side.
However, much different from a FM debate, a theoretical "which one is the better fighter" discussions hardly has use for hard data. The best it can do is suggest tactical choices for the pilot flying the planes, but nothing more.
I don't think there is any reason for some people to be discouraged, since there is no way to 'prove' anything in those sort of discussions anyway.
Oh.. and I already got my neck deeper into the debate than I'd like to be in

Check the ".. uber 109s" thread at the IL-2 forum for my latest response.
ps) If it's any solace, the Bf109G-10 we have in AH is actually more close to a Bf109K-4 than a normal G-10. And.. we DO have a SpitXIV in AH too. So far, most people agree that as a pure A2A fighter the SpitXIV is the UBERmonger of them all.
My personal experience in AH is that unless SpitXIV pilot is a green, the 109G-10 manages a very very disadvantaged battle.