Dr. Zhivago,
I have the results of the tests you mention being conducted by the Air Fighter Development Squadron. They were published by William Green in his book "Augsburg Eagle." The aircraft being tested was a Bf 109G-6/U2 equipped with Rustsatz 2 (two underwing 20mm cannon gondolas) and the standard 30mm MK 108 cannon and two 13mm machine guns. Initial climb rate for the standard G-6 without Rustsatz 2 was 3,346 fpm at 7,000 lbs. normal loaded weight.
All other statistics are essentially correct. The report states that at the rated altitude of the 109G there was little to choose between the two fighters in climbing performance, but at all other altitudes the Spitfire possessed a marked advantage in rate of climb.
Tests against a Bf-109 G-10 would have come out somewhat differently. The G-10, from a standing start, could reach 20,000 feet in six minutes (Martin Caidin, "Me-109"). I don't know what the initial climb rate was for the G-10 upon leaving the ground but it must have been stupendous. The 109 G-2, with 1,474 hp for takeoff had an initial climb rate of 4,590 fpm. By comparison, the G-10 with DB 605DC engine had 2,000 hp available for take off.
Regards, Shuckins