Hmmm..
Coupled with everything said by others in this thread here's my take on the 109G10.
IMHO this is a vertical fighter requiring mainly vertical moves. There are many similarities between it and the P38. The G10 is faster at most alts. The P38 uses flaps allot the 109G's very rarely gets to speeds where flaps can be used. With a badguy on u I usually (depending on speed) nose down gain speed then gentle turning climb away with wep if needed. With 2 or more badguys your tactics must allow for all badguys within 3k and in some cases 4k. Another 109 requires additional caution! You may even want to engage the others with the 109 getting 1st priority.
This plane presents a small target and can be very hard to hit at distance.
I usually fly the 109G10 with 75% fuel and DT. The G6, G2 etc. either 75% and DT or 75%, very rarely do I lift with less then 75% but have gone up with 50%. It has such a small fuel tank.
I've found that depending on speed alt and weight (fuel loadout) the compression factor can change.
Generally 450 mph is the place where compression seems to get bad.
This seems to be from about 12k down. Above 12k to 25k the speed seems to go upward towards 500 and even 550 range for compression.
When i start getting too much speed (425 or so nose down attitude) i will roll left or right and apply hard rudder in the direction of the high wing. The roll direction depends on my target. Hard turns with this flight angle will also bleed allot of speed.
300 to 400 mph is best fighting speed with 350 to 375 being ideal.
I started flyin this plane against, or because of, La7's.
IMHO the 109G10 WITH GONDOLAS and flown properly is a La7 killer. An La7 above 10k can be in some real trouble against this plane! And if the La7 dives and runs you can follow and catch him if his base is not to near.
IMHO, 1 vs 1, La7 vs 109g10, it is the La7 that is at bit of a disadvantage. This is only my opinion and may be due to the individuals i've engaged more then the actual plane performance.
The G2 and G6 no gondolas (at least for me) are great planes for lower alt furballs if flown properly. And the E and F models can be interesting.
!Cut throttle! while at certain speeds and then nose down or up and hard rudder, elevator, and aileron combinations can produce some interesting results

OK OK I admit it! I love this plane. It just seems to suite my flying style.