Getting back to the original poster's complaint, or rather lack of specific complaint, there is one thing that is really obvious to me from the reference article he links to: In that article, the pilot very clearly describe the Me-109E as a big energy bleeder in turns compared to a Spitfire, and this is WITHOUT the wing slats extended... He clearly states that with the wing slats extended, this Me-109 feature would be worse still (maybe not as bad as he thinks?), meaning that even at a similar turning radius, and with an equivalent or better climb rate, the Me-109E would lose more speed in turns compared to a lot of slower-climbing aircrafts...
This issue points to a basic problem with overall computer simulation flight modeling, where acceleration is treated as being the same for straight-line, climbs, turns, dive or zooms. There is no direct relationship in real life...
There is an old thread here where F4UDOA(?) points out, quite correctly, that the Tempest V has a slower level straight-line acceleration than many other inferior-climbing types, yet had an excellent climb rate, and the countering arguments all went along the lines of "not the exact on-the-nose climb speed acceleration" for where the level straight-line acceleration was tested as it went "past" the "best climb speed"... Typical nonsense... The basic problem is that drag is simply not the same depending on what the aircraft's specific, and unique, shape is doing in turns, climbs or in a straight-line...
I believe the pronounced speed-bleeding in turns displayed by the 109E, in the OP's linked article, likely applies to some extent to all Me-109 variants, and explains why the presumably tight-turning and fast-accelerating Me-109 is matched or out-turned by many heavier types, even perhaps those with less power-to-weight. This is not reflected in the Me-109's climb rate, which is excellent, but this apparent contradiction has led to a very unrealistic Me-109 in most simulations, since they simply do not include a drag that is specific to turns...
The complexity of airframe shape is close to the complexity of natural phenomenons, and thus an over-reliance on math alone will lead to very skewed and unhistorical results...
On that issue at least, the OP chose a good article that illustrates the point well...
Gaston