NaBkin,
There are very specific and accurate methods by which relative combat performance can be measured and those methods are described in great detail on the Navair links.
In particular, for purposes of your specific concern, a side by side test for level flight acceleration will show you, or anyone, which plane has an advantage.
If there is no advantage in level flight acceleration then there is little room to make any claims about the 109 having any advantages, since the 109 with the nasty stall and the significantly larger sustained turn radius and the significantly larger turn rate is modeled as a target in this game.
The historical record describes something described by Robert Shaw in Fighter Combat called Single Superior performance advantage held by both as the 109 had a superior Energy Fighting (BnZ in game terms) envelope and the Spitfire had a superior Angles Fighting (TnB in game terms) envelope.
The advantages either way were not as significant as the advantage held by the FW190A-3 once the Germans entered that plane into combat against the Spitfire V, and the early Spitfire IX, so the "better" fighter between the Spitfire and 109 during The Battle of Britain was marginal at best, where the Pilot was the determining factor not the plane since the Spitfire had only a slight sustained turn advantage and the 109 had only a slight acceleration advantage, so the Spitfire was slightly better in Angles Fighting, if the pilot knew how to fly close to the stall, and avoid spinning the plane, and the 109 pilot has a slightly better Energy Fighting advantage if the 109 Pilot knew how to avoid entering a fight with a better Spitfire pilot who starts the fight with an Energy Advantage (such as a better Spitfire pilot attacking from a higher and faster position in the rear hemisphere of the 109).
If you care to know about a very good test that can be done to measure relative combat effectiveness between two planes then I can describe Robert Shaw's Sustained Turn Technique in detail, and you can try that out in the game, to see what you find out when you use that technique.
You can also read the book yourself.
It is here:
http://www.amazon.com/Fighter-Combat.../dp/0870210599
I can explain the technique with words, and I have used the technique in games. I had an IL2 Training Track File posted on the internet once too. It is a very valuable maneuver to know and understand, and it will show you, without a doubt, which plane is Double Superior. It is an Energy Fighting maneuver, which may not be indicated by the title of the maneuver, but that is what it is, an Energy Fighting Maneuver called The Sustained Turn Technique.