If you are not buff-hunting, most cartoon-pilots benefits from the 20mm in terms of hit probability at range, extra bullets, and less weight.
We have the early G6 with extra nothing ( except the Erla Haube, and Wgr21 for some strange reasons (probably to bait some idi.. er brave pilot to fly it

)
Heinz Knoke's book indicates they got gondolas after introducing the G6, and the Wgr21 later in the war.
Perhaps MiroMorai have data when the R6 and WGR21 where introduced for the 109G6 squadrons ?
Max takeoff weight was 3,398 kilo, not that heavy if you compare with the American later war monsters.