[ojcar]

Sorry to disagree. Nearly all air combat in Eastern Front was at low altitude. Even when in combat reports Soviets were talking about high altitude, this "high" altitude is much lower comparing combat over all other theaters. So, climbing until 10000m is not well suited for Eastern Front.
Same story in Pacific, most of the combat were at low and medium altitude (higher than Eastern Front), with few high altitude missions, including B-29 raids.
High altitude missions are for Western Front 8 and 15 Air Force missions and some Battle of Britain