I probably average a 6-7 to 1 k/d ration in my niki most tours.
Key to a niki vs. fast planes is setup and position. You for darn sure are not gonna catch 'em. I tend to be patient and kill 'em when they get frustrated at not being able to hit me and become aggressive. Just be patient. Typically after the 3rd or 4th attack, they will do something dumb. Just bide your time, and keep your E up and be ready for when they screw up.
Key to a niki vs. turn and burn planes is Flaps Flaps Flaps and Flaps. If you fighting one of the spit's, get slow faster than they do, and try to keep the fight more in ther verticle, i.e. yoyo's, verticle scissors etc.
When I see that the spit driver is gonna knife fight me, I go zero throttle during 'bout the 1st 1/2 of a verticle move until I hear the flaps deploy. Then i'm constantly tappin' flaps, and fighting like crazy for position. Wep on the way up, chop throttle on the way down during moves. The key is to get in position on 'em before the spit reaches stall speed, as then they gonna have an edge on ya'.
(and ghosth, saxman, i'll turn/burn vs. a F4U any day of the week. A well flown corsair can give a niki fit's with rolling scissors, but the niki can hold it's own, and once down slow should eat the F4U for lunch)