I think there's a big reason why the Spitfire gets over 3k kills more than a 109k in our current tours. Most kills last tour of any plane. and a 1.4 k/d last tour, which is pretty high for that plane...
The K4 usually gets a better K/D as it's a little easier to stay alive not getting tied up turn fighting, but its much harder to get kills in overall due to 1 cannon vs the spits amazing cannons and 50s, and takes a lot more ACM understanding to be successful in it over the spit16 due to views and plane flap handling. The spit16 still pretty easily out maneuvers the 109 in a turn stall fight given the same relative E but a good pilot can make it very close.