Well first, I have a wagnload of virtual air combat expirience im multiplayer online with IL2 and I was damn hot at it against humans.
In IL-2 you couldn't turn with the Spitfire no matter what(which was wrong, Spit was uber turner at low speed but not at high), not an inch, zip, nada, here it's quite possible.
BnZ is basically entering the fight at higher speed and/or altitude or higher energy, but you know that already. Against Spits(first flight with the expansion), I just entered the fight at very high speed, broke their formation and zoomed up, after that to my dissapontment they had apsolutely no chance at all. Even simple loops worked, and yo-yo's were like magic insta-kill solution. Ofcourse they killed my whole AI flight so I had to fight them alone grrr.
Like I said that was boring so I tried fighting them, magic formula was, lag pursuit in a turn, when he stops turning hard G snap turn(real Stang would stall here) into him, trrrr goodbye - repeat.
Actually according to my present expirience with the game I would say MiG-17 is a better turnfighter than a Spit...either that or default FM Stang turns too good.