Where do you get that it was more maneuverable than the 109? High wing loading was one of the reasons test pilots didn't like it, due to high landing speeds. This is a problem that not even the Fw 190 had, which is one of the worst turning fighters in the game...
What killed the Luftwaffe in the BoB was poor tactical and strategic decisions, lack of fighters and the short range of Luftwaffe aircraft. The He 100 would have only helped one of these areas, and would have made the lack of fighters even worse, as even if the He 100 could have been produced as fast as the 109 (which I doubt), one of the ingenious points of the Bf 109 and other Messerschmitt designs was that they were easily serviced in the field, whereas the He 100 was the opposite of this.
I think the He 100 would have probably have been like the MiG 1/3; sleek, sexy and fast, a good propaganda tool, but a dog of a fighter, and I doubt it would have been able to make any positive difference over the 109, which proved to be a very versatile design, considering it was still one of the best propeller fighters in the world on May 9th 1945, which was WELL passed the point where it was supposed to be phased out.