Y'know, this subject comes up every bit as often as complaints about the flaps....
To start, take all the good points of the other F4Us (excluding the cannon of the Charlie) and tack on about an extra 500HP, a four-bladed paddle prop and I believe a little bit less weight (especially as compared to the 1 and 1A, which carry two extra fuel tanks).
The fighters you mention may be able to run on or extend in a sustained climb on the deck, however with the exception of a VERY well-flown La-7 the F4U-4 will hand all of them their tulips in a close-quarters fight, and this is at all altitudes (assuming equal pilots). The F4U-4 will also zoom on each one of them except for MAYBE the K-4 if she's Co-E or better (equal E-states the 4-Hog will catch or lose the Dora, Pony and La-7 in the Zoom). Acceleration is vastly improved over the 1-series Hogs, as is level climb. Combine this with the fact that Corsairs already have among the best E-retention in the game. Rate of roll is superior to all with the possible exception of the Dora, and unlike the Dora and K-4 the F4U maintains almost total control at nearly all speeds until you begin to exceed 550 TAS (the German Iron starts to suffer control stiffness, especially elevator authority, well before then). Then of course there's der Uberflappen which really goes without saying.
The only flaw the 4-Hog has is range on internal fuel, but she doesn't suffer a drag penalty once you cut the DTs loose since the pylons are fixed so taking them along hardly needs a second thought.