Sorry, but i find your arguments a litlle bit biased, since you not only doubt russians figures (what is reasonable from other experiences), but german statements. I can't remember to read anywhere, that russians data claims were over. Pls show me that sources.
Rall made clear in his book, that his statement is for those, who think russians weren't able to build well planes. If you keep in mind that most dofights at eastern front were mostly under 4000m and you take both sides official numbers in aspect, you 'll see he is right. maybe 10-15kph didn't play that great role and also maybe nominal perfomance was more important.
Barkhorn statement is also founded by Walter Wolfrun: "The best Fighters in combat I met were P-51 Mustang and Yak-9U. Both of these types obviously exceeded all Bf109 variants in perfomance, including th "K"."
Barkhorn knew russians planes very good and was commander of a fightersquadron at eastern front. Yak-9U was introduced in 10/44 at northern front.
Schwabedissen wrote studies about eastern airwar for USAF. The americans had no doubt about this, due their own experiences in Korea. The fighterbombermissions were flown by NN in 1944/45 like Schwabedissen stated.
some La-7 test of the -39 is here:
http://www.btinternet.com/~fulltilt/...l#No.452101-39
the other number isn't really comparable to other la-7 numbers.
Factory data of La-7 seemed to be reached with polished skin and so on, which i think was more or less normal for german tests.