The problem comes in if you're up against a Hog stick who knows how to maintain his E and position. An experienced Corsair pilot knows not to scrub his E to turn against a Spit for the exact reasons described by BnZ. He'll keep the fight more open, where the Spit is at something of a disadvantage.
Co-E, or even at a small disadvantage the Corsair is by far superior in the zoom, so can actually catch or lose a Spit in the initial part of the climb. Additionally, while the F4U has various tricks to dump E more rapidly her greater mass ALSO allows her to hold on to energy better as well (thus the better zoom, which may be one of the best of any ship in the game). The Corsair remains controllable at airspeeds the Spit can only dream of. While acceleration in the initial part of the dive the F4U needs a little breathing room, once she starts to wind it up the Spitfire will find it very difficult to keep up. The Hog's rate of roll is spectacular at all speeds so can be difficult to keep in-phase to begin with, but this actually IMPROVES as airspeed piles on. Don't be surprised to see a Hog in trouble point that big nose down and start rolling like mad to throw you out of plane. Chasing the F4U through a zoom climb can be a very dicey proposition. Besides the fact she'll open a bit due to her superior zoom, you MUST watch for wing-overs at the top of vertical extensions. The Corsair has a VERY effective rudder (rudder authority in the F4U is one of the best of any other ship in the game) and can haul herself over almost instantly and give you a face full of .50cal.
You also have to concentrate your fire. The Corsair won't soak up ammo like some aircraft, but she's still a tough bird and if you're not hitting her consistently and in-convergence she can be frustrating as she flies through a hail of machine gun and cannon fire and escapes a little dinged up, but intact. The horizontal stabs, outer wing panels, the fuselage immediately aft of the cockpit and engine are all particularly vulnerable to fire, and are your best aim points (this is in opposition to the Spit, which will fall apart when hit pretty much anywhere). Don't count on one-pass kills unless you're able to really get saddled up.