How about:
Hurricane kills / Hurricanes lost = 656/317 = 2.07
Spitfire kills / Spitfires lost = 529/497 = 1.06
So the Brits traded 1 for 1 with Spitfires but got a 2-fer with the Hurricane.
You can bend the numbers many ways.....
...and there were 50% more Spitfires than Hurricanes.
Not trying to bend numbers. Just trying to reconcile the conclusion offered by the referenced article with the numbers/data that the article offered.
So I guess my next question is which facet is a better indicator of "combat record"? Kills / Acft? Or Kills / Acft lost?