To follow on from CirX post, if you aren't happy with the balance in the stock campaign, you can always change it. The stock Il-2 Bf-109 campaign is a static campaign, hence you can edit the mission files. I did this in the past to add in the new aircraft and in fact for the missions after 6/44 I replaced the G-6/AS with the G-14/AS. There is going to be another revision of the 109 pack in coming months, so some 'oddities' will be ironed out or reassessed.
Just to recall my point about the DB605 engines, I can't find the reference I had (lost my bookmarks list) but from memory, the AS engine was introduced into service in February 44 (cleared for GM1 usage around same time). AM engines arrived around April-May and I believe ASM engines around June/July. This again lends support to the argument that few G-6/AS aircraft had the DB605ASM engine and looking at service records on the Western Front, appearance of the engine in service corresponds with the deployment of the G-14/AS on the western front in July/August 44.
I like very much your effort and historical research for obtaining the best possible realism. I was not able to detect any "oddities" in v3.1 apart from one - we have the "hotrod" G-4 that goes like crazy and outperfoms almost everything in its way (however, for late '42 this is historically correct) and then we have a late G-6 with only 1.3 atm. It appears that most of G-6 that had both the erla and the tall tail were build from late '43 until mid '44, so even if we believe 100% that 1.42 appeared only after november '43 (sorry, I doubt) then a 1.3 atm late G-6 is an oddity, a plane that possibly existed in reality, but most likely a rarity.
Impressive are the performance differences between G-14/AS C3 and G-10 C3, who 's the gifted one that did the FMs?
A suggestion - why not re-introduce G-6/ASM with G-14/AS 3D as a G-14/AS B4?
EDIT: I hope for a seperate (I fully understand that some people find them too many) pack that will re-introduce the "lost" Bf 109s as we knew them in UP 2.01. I am not asking for anything new, only something that already exists.