Interesting. Although the AA guns could have made good defenses on the east, the big problem with heavy AT guns were it's mobility with the german army retreating, they leave a lot of them in the mud as soon as the little transportation system that they had have a problem. Aditional, if the bombers doesn't have the risk on lower alttitude from the AA guns, they could have drop them so close that they could have destroyed the industry and cities at greater rates.
Main affect of AA defences on the war were in reducing friendly ground casualties by encouraging less accurate bombing (from higher altitude/less pressing of attack). Without dense AA defences more accurate bombing raids would have been made by BOTH allies and Axis air forces. This could have had major affects on the war effort of both sides through a more effective blitz (lets ignore the idiocy of starting the blitz on London just as RAF defences were almost completely smashed).
One unfortunate result of such effectiveness is that it lead directly to mass bombing of population centres rather than precision bombing of factories - leading to the horrendous civilian casualties of the late war period in Europe and Japan.