Gonzoville stats say the 109F4 turns a little better than the Spit9 with no flaps and marginally worse with full flaps. Looks to be a little faster.
Spit8 and Spit16 should be handing Ki84 its butt, not the other way around in my experience.
The fundamental flaw in the anti-Spit argument is it generally comes from guys who have moved on and have learned a lot more about flinging cartoon airplanes around. Put them back in Spits and they can tend to wreck the place. But the Spit was that kind of plane. Forgiving, easy to fly, and capable. Throw in that guys in birds that don't turn as well, get mixed into dogfights with it, and it can get frustrating.
I'd rather see a hundred Spitfire 16s then 100 Mustangs however as the odds are much greater that the Spit drivers will stick around and at least try and fight. Odds are good that in that 100 Mustang drivers, maybe 5-10 of them will actually know how to bend it, and stick around. Interesting to me how many of those real ETO Mustang drivers started in Spits, then hated Jugs, then loved 51s as they were more like Spits!
With the Spit new guys can gain some confidence, take some 'risks' and learn about cartoon ACM. And with luck, if they stick around, they'll challenge themselves with tougher birds.
As for 84s. I'd suggest the guys flying 84s know them a lot better then the majority of guys flying Spits