i think the spit xii is just as fast as ki 84 and 190a, but won't outclimb planes like spit 16 and 109k
and i doubt you can turn and burn it since you got a slightly heavy griffon engine. Heck I don't even turn and burn with spit 14 in dueling arena furballs.
Again, trust me on this one. I'm guessing you've discovered the XII recently. It's been my baby since 1980

Standard tactics with the XIIs were to troll below the 190s and 109s. They'd break into the 109s and 190s and have at it. Best day being October 20, 1943 when they got 9 for no loss after being bounced. It turned just fine and was put into production to stop 190 hit and run raiders on the south coast of England, which they did, most effectively on May 25, 1943 when 4 Spitfire XIIs of 91 Squadron caught 12-15 190A5s and shot down 5 for no loss.
I fly my cartoon 38G the way I do because of those Spit XII guys. I like to fly low and try and suck em down and see what I can do. It's burned into my cartoon pilot brain to fly it that way.
Would I enjoy the XII? Sure. But do we need it in AH? Not before a lot of other birds come first.