From: Bristol, UK
I am sure this is known, but we have to be careful when talking of fighter vs fighter action not to think of this as the same as dogfighting.
Dogfighting is usually considered your classic 'WW1' turning fight although by WW2, many of them were 'vertical turning fights', that is with 3 dimensions (rolls and split S, Yo yo manoeuvres etc).
In game this is air combat as a whole not just a dogfight. The best theoretical fighter of WW2 would be one that is fast, high rate of climb and dive, good detection ability (good cockpit view and better radar than yet invented), gyro/tracking gun sight and adequate weapons. It would then spot the enemy first, put itself in a optimum position, bounce the enemy at high speed, open fire at greater than 600 yds, score a kill and return to the heavens. Any ability to turn is strictly for air displays.
Now this aircraft obviously doesn't exist, but to the extent it can be modeled in game, it should have negligible losses and either high kills (sees the enemy first) or a 0:0 draw (enemy sees it, and prevents the bounce) - all assuming adequate supplies and competent crews.
The classic example of air fighting is P40 or F4F vs Zero - Zero better in most respects and won in RL for a while, until the US (particularly) stopped dogfighting. They bounced a Zero if they could and stayed well away if they couldn't. The Zero then starts suffering. This is effectively what 'Exp' should be giving in game... low exp aren't only flying the plane 'worse', they are using it wrongly...
So, back to where we started, extra cannon pack 109Gs cant just be assumed to lose to basic 109s, unless the effect on flying characteristics is so pronounced as to make the a/c unflyable (unlikely). But high Exp/Mor pilots on both sides have to be assumed to be flying each to the best advantage... the Cannon pack will be trying for a bounce and completely refusing to turn (dive away instead). The basic 109 will be avoiding the bounce, and then turning. If the delta is very pronounced they may even encourage the bounce to start to get the attacker to come down to fight, then turning the tables on them, as some of the best Tempest and Spit XIV pilots did late war with LW a/c/ that would not engage...
Oh, and the test needs running lots more as said elsewhere.
I have a cunning plan, My Lord