It looks like, from the climb charts in AH, that the Spitfire Mk Ia and Bf109E-4 have nearly identical climb performance for the first 8,000ft, after which the Bf109E-4 pulls away.


The information I am familiar with has always indicated that the Bf109E-4 climbed significantly better than the Spitfire Mk Ia.
Initial climb rate of 3,280ft per minute, and 7 minutes and 45 seconds to 19,685ft for the Bf109E-4.
Climb rate of 2,530ft per minute and 9 minutes 24 seconds to 20,000ft for the Spitfire Mk Ia.
If this is correct, it seems that the Spitfire Mk Ia climbs too fast in AH.